I ran a 57 Chevy 283 "270 hp" in Junior Stock back in the 60s. We were allowed 55 lbs. on the valve seats and I saw 7200 rpms every run. Of course that was a solid lifter cam and the springs would fall off real bad after 10 to 15 runs. I run 90 lbs.on the seats,194/160 valves, opened up pockets,NO LUMPS,zero deck,flat top pistons and 262/ 500 lift cam by Lanati in my 250 and like you say 6000 is no problem..but from 5000 on it just stops pulling hard. As some one on this board said "not too much cam..Just not enough motor".. The balancer issue is something I need to look into more... J
