With my Athena I used the high comp metrakit head(Graham's relocators worked great for the stud spacing). I did my own case alumaweld job like cheetah's cases and thoroughly case matchedall the way down, not just chamfered. I also dowel pinned the cyl to case, and pinned the head to the cyl so nothing could move around( a benefit to keeping the 6mm studs!)
I would have had piston to head contact with a single base gasket- so I did some ball sanding in the head and got it out to about .3 squish. Then I cut my own "spacer" out of sheet metal that was around .53 thick. That combined with 2 thin base gaskets- single Athena head gasket- I thought it'd be too much but when it was all finally torqued down I ended up with about .8 squish in the end. I'm guessing I'm somewhere in between going deep in the head and/or decking the cyl with the 1mm spacer. A happy medium-
With TJT, H95, stock belt, and still using the single .35 reed on hogged out stock reed block, 21 dellorto kit, 77cdi w/jog box I already had. Temps are low 400's after extended wot, on hot days maybe 435.
I've already put about 600-700 miles on it since the build- still ripping HARD and easily out front among the fastest bikes at any ride or rally(some go faster overall but no-one can touch me till I top out). Pulls my 210lbs and it's own hefty weight(hydro forks, mag wheels, disc brake, etc...) up to 55 sitting upright with face blistering acceleration. A tuck gets me in the 60's on flat ground- Have gone over 70 but that was downhill.