Since they're off the car right?

First see if the GC top hat fits over the body of the damper because in the pic it doesn't look like it will.
Do this by removing only the bump stop and spring.
Also measure up the fully compressed length (you'll need two people for this, one to compress and one to measure) from center of clevis mount hole to the part of the top hat that rests against the chassis (most likely where your palms will be pushing to compress the damper) and be sure the top hat is as flat and square to the damper as possible.

If you can't get a helper just install a damper without bump stop and spring and jack it up from the ball joint (if the damper on the opposite side is still installed then you'll need to either disconnect the sway bar end link or remove the other damper) take your measurements from the same place (the point where the top hat contacts the chassis and the center of the clevis bolt or head)

Once I get a better pic of the diagram I'll explain how they go together but I think you might either be missing a washer or the bump stop will get pushed over the misalignment bushing.

 

The shock bodies, do not fit inside the GC extended top mount lower boss. The shock body and top mount opening are about the same size, at 2". Will I need to trim the lower boss, for more travel? How would you determine how much can be safely trimmed?

I do have the metal washers, forgot to put them in. Although the other parts I don't have, I'm hoping I can re-use the factory sleeve, bushings, upper spring perch if they are needed, and not sure if I need a separate spring isolater like in the diagram? And also if the silver metal sleeve resting ring in the close up shock pic is needed, or the sleeve just rests on the circlip. Either way the threaded sleeves are not "secure", they are just sitting on top of either of those pieces, and can spin around the shaft freely as well.

Also the diagram shows very clear/text readable for me, did you try clicking on it to enlarge or download it? Or let me know which part you need to see more clearly.

Removed spring and bump stop, used washer under top hat, fully compressed length is around 12.75" from center of clevis hole to the top flat surface of the top hat where the 2 nuts screw in. Once released, it slowly decompresses by itself to around 18.75". Is the difference between these the stroke, without ride height limiting bump travel?

 

My replies to comments are in blue
My gut feeling is you'll need to run stock top hats with like a 10 mm bump stop for the rare moments when you do use up the travel which you will at that ride height.

 

So if the ASTs are 11.5" from clevis center to top of body and I'm running the OEM tops with the rear being around 13" ride height do you think I'll bottom them out? 600lb springs in the rear and the bump stops are shortened AST stops but still at least an inch tall.

 

Oh, wow, so due to the longer compressed height, they use more bump travel than stock? Don't they still allow the bump stop to fit inside, allowing a longer bump stop that takes away less travel? Also, what if I trimmed the lower boss some, would that add travel, and how much could I trim?

So 1"+ will be my usable bump travel? How did you calculate that? I don't know for sure if 12.25" is attainable, but I have seen other members with 8" springs at 12.25", though they have 10.5" length shock bodies. You think it's a good idea to cut the bump stops down to just 10mm? Wouldn't that make them very stiff and loose the smooth engagement these ones are designed for?

So if I am using 2.5" springs, would it work without the isolator? Is it okay for the threaded sleeve to spin around the shock body?

That sucks, was hoping I was adding travel with these top mounts, not reducing. I am planning on having this all installed tomorrow. Let me know what you would recommend as to which top hats should allow the most travel, how low of a ride height I should try for, and what length to size the bump stops. Thanks, appreciate the help!

 

just an FYI:
I emailed Hyperco the other day to find out the block height of a few of their springs b/c I haven't been able to find them posted on the webs.
60mm ID 5.5M0750 2.284” solid height = only 3.216" travel
60mm ID 6M0700 2.595” solid height = 3.4" travel
60mm ID 7M0700 2.979” solid height = 4.021" travel
2.5" ID 7B0750 2.964” solid height = 4.036" travel

I am in the process of upping my spring rates to either 700 or 750 rear and 750 front. Since I have limited travel back there b/c the shock bodies, I'm trying to determine what springs to go with and if I will have to run bump stops and what ride height makes sense for me to run.

Looks like I'm just going to use my current 60mm 6" 700s on the rear and be very close to being able to bottom out the shock on the upper mounts but not quite. I'll need to run a small bump stop just in case.

I want 750s on the front so now I can only choose b/t the 5.5" or the 7" spring b/c 750s are not available from Hypero in the 6" flavor. Need to run some measurements to see if I can run the 5.5" springs successfully.

 

Answered in bold

 

Does't the above mean the stock length was 13.75", so at 12.75", it should have more travel, or is this a different measurement?

I called GC, they said the top hats are not designed for the shock body to fit inside them, just the bump stop, and it will give up to 1" more travel.

Also will trimming the lower boss on the top mount free up more travel?

They also said I don't need any spring isolator/seat, can just put the spring up against the top mount, but with the stock top hat/perch/seat setup they didn't know if it was flat/secure enough to hold it, anyone know?

So despite short/stiff stops often making things worse, with stock length shocks like my setup, you'd still want the shortest stop possible with travel so limited?

Maybe I will start out at 12.75"f, 13"r, and measure the travel and go from there, to see if I can go lower 1/4" at a time. Thanks again for your help!

 

13.75 is with a 40mm bump stop compressed about 5mm so no

If GC did not design it so the body fits inside then they designed the bump stop to reach block height before the damper body reaches the spring perch capture ring. Do not cut the GC bump stop

You're kinda screwed, a larger stop usually means a larger block height which means that much less travel. It really depends on whether you will reach that block height (I think you will) and if you do this is when things will become interesting. You'll either need to raise the car or increase spring or roll rate.

It's hard to explain but reaching block height of the bump stop through a corner is worse than occasionally reaching a much quicker ramping stop.

 

That's interesting..when I talked to GC another time, they said it was fine to cut the bump stops, and just go bit by bit, shortening it until it stops bottoming out on it, down to the last 1/3rd. I have their soft shock progressive 54mm bump stops, still confused on what length to run them at front and rear, guess I can start at full length and see how it goes. Hopefully when we install can test out the travel to see how much there is and see where it bottoms out.