So with those figures, is the median measurement the ideal setting?

 

I run the tighter clearance on both.a tight 8 in intake and a tight 10 on exhaust.

It forces you to check them more often with the tighter tolerances, but the benefit in performance is worth it.

 

How much of a performance benefit would this be??

 

I highly doubt a dyno would show a 1hp increase. Running exhaust at .10 is supposed to make them a little more quite. A valve adjustment is a PITA the first time. Then it is gravy. You live in a big state, so finding someone to help for the cheap shouldn't be hard.