Tim, The cast pistons have got to go! Get a set of TRW #L2404F pistons, they are cheap enough [$255.00-Summit] 19cc cup and with the A2A heads [92cc]should put the compresson at about 8.25 to 1. Get a set of truck/CJ rods & a set of ARP bolts, shot peen the rods and recondition. The cast crank should be good for about 6500+ rpm if you stud the mains, again ARP will work great. Have the block bored with a deck plate and have the block square decked and align honed. With all this done the short block should be good to about 6500 with the rods being the limiting factor here or you can step up and get a set of Eagle rods, about $700.00 for extra ins. I would limit boost to about 10lbs for safe operation and keep it from detonating, run good gas [racing mix] and read plugs. My engine is a 4 bolt block [steel splayed caps] Moldex crank, Crower steel rods and JE pistons with a 20cc reverse dome. A little overkill as I did run a stock short block/with the above forged pistons with no failures with exception to a few burnt pistons and lifted the heads a few times but no bearing failures, main cap walk or broken rods ect and I wasn't kind to it either.