90.5 and 94 are the same thickness. Just more heat with more surface area.
Read the engine tech articles at
www.cal-look.com and
www.aircooled.net and you'll figure things out. A nice setup is the 4340 82 stroke vw rod journal stroker from CB performance
www.cbperformance.com and 90.5 p/c set. Buy a set of 044 heads 40x35.5, a 1.5" merged header, dual 44 IDFs, build it right, and you'll get 100K miles out of it and make a reliable 130 horsepower. A C/R of around 8:1 works. Don't go too high.
Steve