@Dan the man I'll put it straight out there: It's gonna be some kinda street cruiser, right? Little bit of pep to do a burnout, good acceleration, make some noise, have fun? Right?
Well guess what: headers are a big part of this. Like I said: get the cheap summit branded headers. Forget about messing with manifolds. You're leaving a lot of torque and power on the table if you stick with manifolds.
Honestly headers are the first thing I've always installed.
It's real simple.
1. Get a car, with the biggest engine that's in good shape you can find.
2. Treat the engine to good parts (headers, intake, carb, camshaft).
3. Go burn rubber till it gets boring.
4. Repeat steps 2&3.