The rear axle is most likely a 7 1/4" axle with 2.76 or 2.94 gears. The engine you have now, once running correctly, will destroy that axle in short order. I would spend money upgrading that before spending $$$ on a converter.
With that cam you should be able to get a smooth or at least steady idle at 800-900 RPM. Take the time to get it set up and tuned right. Your basic package should have good power, good street manners, and get 20 MPG.
Here's my advice:
READ AND UNDERSTAND the manual that came with your carb (Edelbrock 1406?). Everything you need to know is in there in plain english.
Make sure your distributor is functioning correctly. That is, both mechanical and vacuum advance work.
Make sure you don't have any vacuum leaks (sounds like you may).
PCV is a good thing, run it.
Your heads were cut .030, why? To raise compression? How much material was removed from the intake mounting face?
Are you running rubber intake end seals or RTV?
What is your lifter preload? Since the heads were cut .030, did you order .030 shorter pushrods?
