360-383 A-debate...max builds need not apply.

You could be right.

I have heard that the 383 was the base motor in some model E-Body, and the 340 an upgrade, but it seems like the 383 was always rated higher than the small block. Maybe just Dodge playing with the numbers?

Couple of things I can think of that might throw things off:

1. The bigger bore of the 383 might help with the intake valve flow, making things more even.
2. The 383 is still more cubes, even if it is the smaller big block available.
3. Valve train geometry is probably better on the 383.
4. Dry intake. No coolant flowing through it to warm it up (or cool it down??).

Wish the guy who used to post all the old road test data and drag tests was still around. I bet he could give us a comparison between a 383 and 340 Dart.