I don't know a lot about the 67 , they would have had 516 heads and I think it was based off the 300HP 383 , the left manifold was more restrictive on the 67 , they changed the manifold for 68 and used it on 69. I never compared the specs on the 68 , based on the lower HP engine, and by the way the 68-69 330HP 383 used the 2bbl cam.

What I do know is the 69 330HP 383 used in A bodies only is the same engine as the 335HP engine , same cam , same heads , same carb on the 4 speed , auto ??? the A body 383 had a dual point distributor , the 335HP engine didn't. I'll guess the 5HP difference is that left manifold.

This spring/summer I'll finally have the replacement engine for the Dart on the dyno and I intend to swap the exhaust manifolds to see how much HP difference there is .