Personally I dont think that I would go after a 76cc combustion chamber head to make up what ever CR I was tring to achive. I would be affraid that it would be too large of an area to maintain a good "burn" or quench pad area. I would not go any larger than a set of 72cc heads. If you where to use a 72cc head and a flat top piston then you would end up with 10.2:1 compression which on a motor with alm heads is easily run off of pump gas, heck my 11.2:1 CR motor can and has run on pump gas.
Dont let a good quality dished piston fool you, they have D dished pistons now, they are not like the old O oval dished pistons that had horrible quench pads. the D dished pistons are shaped so that they keep the same style quench pad as a flat top. I had 18cc dished pistons and made just over 500hp on pump gas with them, these are the same ones that I have in my gargae that still look brand new.