I'm currenty building a motor for my 1956 pontiac. the motor i currently have is a 1977 350 four bolt main. I'm currently running 372's for gears. i already have a cam with 284 duration with good midrange HP for it and performer intake. I'm looking to get a good mid-range HP out of it. It's my summer toy and is taken to the strip now and then. I've considered vortec and 305 heads... I'm trying to build this motor on a decent dudget. and is it true I cant run factory rockers with that cam?