[NoSlow5.0]

Yep, you need 351 based headers for chasis clearance. Making 600-650 NA will be very difficult on a budget. A better way to reach that #would be a 408 with some decent parts and a little shot of juice. I am building the same thing and I already have 5K in the short block and cam. The heads will run me close to 2K, then there is all of the other little crap like oil pump &pickup, intakes, head gear, pan, dress up crap, water pump, etc.. My 408 will make a little over 600 na, but i will put out a lot of $ to get it that stout. If you are making that kind of power you want at least a 900 carb. I am putting a prosystem 950 on mine to start. Looking for over 800 on the bottle so i will get an 1150 when i plan on starting the spray. You can also buy a cheap stroker kit from lots of people that will be nice on the street as long as you don't try to make insane hp out of it. Good luck.