Parts needed for a 350-400whp 302 carbed.

350-400hp naturally aspirated with (unported? iron? p/x?) gt40 heads and a 600 cfm carb is... less than possible

To get that out of an unstroked 302, you're going t need lots of compression, a very healthy cam (you'll have to deal with a rough idle) and high rev capabilities. You're gonna need some serious flowing heads, i would say nothing less than AFR 185s (NOT gonna happen on GT40s unless God himself ports them), and a Victor Jr intake, and that vacuum secondary 600 isn't nearly going to cut it...look for a 650-750 double pumper. Even with all that, 350-400 at the wheels is going to be a stretch and it'll likely happen at or past 6500RPM.