The limiting factor on making power is usually the traction, if it spins the tires your going no where fast That being said with a decent to good set of tires I would put the biggest C,I, motor I could afford, it is a lot easier to drive a car with your right foot to control the pwer that it is to stick your arm out the window to help make power by pedaling your arm in the wind when you don't make enough power If it was me I would build a 511 or 512 out of the 400 block, I have several of those size motors and they flat rock Another option is a 505 C.I. 435 bore with a 4.250 stroke with BB Chevy rod journals, I like and use long rods, 6.8 and 6.7 long No matter what C.I. you decide to build make sure and use the BB Chevy rod journal sizes, 2.200 and a long rod The Edelbrock heads flow more air out of the box so comapre costs and decide. On the cam and headers I wouuld go big on the headers and exhaust, 2.0 inch primarys, 3.5 inch collectors and three inch exhaust to three inch in and out muffs I like the Magnaflow 14x7 x3 inch ovals, basically straight through and fairly quiet at idle and part thtrottle driving, not so at WOT On the cam I would, and have use the Comp Cams XL-HL cams, either the XE-285-HL or the bigger XE-295-HL, installed them 4 degrees advance or a liitle more On the rockers a lot of the ductile iron rockers won't be the advertised ratio, usually less when checked at the retainers I would, if you can afford it, buy the good Harland Sharp full roller aluminum rocker arms, not the cheaper extruded aluminum non roller shaft ones they now offer Make the compression ratio between 10.0 to 1 and 10.75 to 1 depending on the elevation you run the car in, in higher elevation run more compression Good luck