Not to hijack this thread, but I plan to do something simaler, I'm trying to do 400 HP with a stock '70 roadrunner 383. It already has a 440 cam and 9.5:1 compression. It has the CH4B (I think) Aluminum Edelbrock intake from 1969. I have aquired a Holley 670 Street Avenger. I'm pretty sure that the 1.75" headers are the thing I need for the exhaust with 2.5" exhaust pipes. Does this sound like the right recipe? I'm trying not to mod the internals, it's a recent rebuild. Any suggestions on the header brand?