Our nemesis was a carburetor restriction- - - -The only carb we were allowed to run was a Holley 7448 350 CFM 2 barrel. It acted like a restrictor plate and made it useless to run a super-radical cam, big valves, and high compression if the engine couldn't breathe. The 350's were hard-pressed to run 6K or a little above. The answer was 100 cubic inches less engine and a valve train that let us spin the little engine 2000 RPM faster. A 3.1" stroke 262 V8 crankshaft in a 305 block with 4-bolt main bearing caps and H-beam rods, plus a rev kit made the little engine sing! A set of angle-milled 58CC heads that checked out at 40-something CC's with bigger valves and some pocket porting helped, too. Every casting number on the engine indicated it was a 305!
Jerry
