I hope you won't make the mistake of using flat top pistons with the 64cc double hump heads. My advice would be to use a set like these. Keith Black KB193-030 Hypereutectic Dish Pistons 4.030 Bore | CNC Motorsports | Car Parts | Truck Parts | Competition Engines
. A Fel-Pro Q1094 head gasket. I am not a fan of thumpr cams (all show no go). I would suggest Comp Cams XE274H-10. Also another good cam would be a Howards 112581-10. With these pistons, head gasket, double hump heads, and the XE274H cam you will have a static compression ratio of 9.674 and a DCR of 8.176 which is excellent for pump gas. Also your quench will be .040 which is recommended. I would guess this setup would produce about 380 hp depends on how well the heads were ported. If you choose to use flat top pistons your compression would be 10.381. You would have to retard the timing to use pump gas which does nothing but reduce power.