2/3 hrs for an engine change is very optimistic I think. I don't think any engine change is any easy task really, and if you dig a bit, you'll find that more often than not, people do struggle to get these lumps in and out.

A leak down won't give any indication of the oil control rings conditions unfortunately. If oil consumption doesn't bother you, then ofcourse is not an issue.
I have also read (especially for AP1) running for not that long before having crank bearings failing, due to lack of care from previous owners (engine run low on oil at some point of its life)

I totally agree that these are bullet proof engines IF the engine had been taken care of.
I can't stress how critical proper maintenance is for the life span of an engine. I mean no issues with buying a used one with no history, you are just rolling the dice.

anyway, here's a super cool video of a F22C, showing gunged up control rings

 

Inspection of the spark plugs could reveal a burning oil problem.

 

This is what I did in 2011-2012. Bought my car a car for a heart transplant. Donor car got T-boned and was DONE........ like you couldn't remove the floor mat from the passenger side it got folded into the metal floor pan. The tube running under the windshield behind the dash bent wickedly. Sold off the rest of the car in parts down to the frame. Was very glad to see it go & don't want to know what happened to it after it went away. Thanks Mongo!

 

On our car, if you can pull the motor and trans together out the top ( have not tried it but does not seem unreasonable) then an engine swap could be pretty quick. If needing to separate them then there is lowering the subframe to get to the top trans bolts as well. But, I have pulled and installed a motor an trans bolted together in an ND1 with no issues, so I would suspect that is not out of the question on the s2k just at glance. Only challenge is that the motor sits low and you have the cross member in the frame right in front of it. This is all talking us general plebs doing stuff on jack stands and not a lift. With a lift I think swapping a motor may be faster just dropping trans, motor, subframe and all out the bottom.

 

As I understand it, out the top together is complete no go. People find it easiest to remove subframe with engine and trans still mounted to it, then lift body up off, slide subframe out.

Obviously this requires lifting body quite high, not everyone has setup to accomplish that. Hence plan B is drop trans like a clutch job, then pull motor from top in traditional manner. In other words, lotta work.

 

There are videos of people pulling it from the top with trans connected. The tricky part is that a lot of engine cranes do not extend far enough to get over the motor and some modify the crane to make it work which you have to be very careful with or find a crane to do it. This guy does it by modifying the crane and that can put the load in a bad way on the crane of course. If you had a means to lift overhead (chain fall) from something sturdy enough this would not be hard though. Or a crane that can handle the reach/load combination. The vid below shows it done with a hoist but he also modified the hoist so it is likely working over its load limit which is sketchy. Like I said, chain fall from above is likely a lot better if trying to do it this way. Not that I have not done sketchy shit with an engine hoist though

 

Use an engine strap &i removed hood. I removed crank pulley,engine mounts,disconnect gearbox mounts.split bell housing and left box in.loom unplug, ect ect..
and did on my own.. Oh and to add 2/3 hours is just saying stripping engine is a gamble as apposed to ripping and engine in&out,as too a possible failure in opening an S2000 block up..