The '73 is BUILT rich, the 2-barrel is choking the engine.

Ditch the 2-barrel and the carb. Buy a new Holley 670 Street Avenger and an Edelbrock Performer RPM.

A 400 is basically a larger bore 383 with low compression. You can definitely go too big, again I say the second Voodoo cam from the smallest would do all right.

Get your exhaust system right. If you can't find HP exhaust manifolds for it you can use the low perf ones but go to 2 1/2" system from manifold to rear end, using two Dynomax 17748 or 17749 Hemi Turbos. Be sure to put in an H-pipe, that's a pipe connecting the exhaust pipes to each other, should be the same diameter and as far forward as will fit.

With all my changes you'll pick up at least 50 hp with no decrease in fuel mileage, probably an increase. The car will feel completely different. It's amazing what a simple 4-barrel swap can do.

R.