Edelbrock Performer RPM Air-Gap will set you back $350 from Summit or Jegs. The Pro Products copy is about $210 from same places. They are both tall but your other choices mean redrilling the intake flanges on the heads.

Don't mess with the cam. Use a distributor with a decent curve. You may need to use Midgrade gas or maybe even Premium depending on conditions. More cam will mean more work installing better valvesprings and cutting down valveguides. Delta and Bullet are two that'll regrind a hydraulic roller for less than $150.

The exhaust manifolds are OK for running dual exhaust except they may not fit the body. Anyways if you have the 340 manifolds and exhaust system it'll fit better.

Use a Carter P4070 or its Spectra Premium or Airtex clone for fuel pump. Mewchanical fuel pumps suck..literally.

R.