I had a 440 just stuck in a 69 Barracuda, tried the 69 hp c-body manifold, fit ok, just touching the steering column. I then took a grinder and taper ground the gasket face from the top so it tucked closer to the block. 383 will be down and farther away then the 440, about an inch, so you might not need to grind. Any machine shop can true up the face once you get it where it will miss. Go for it, we are hot rodders, we make things work.
I mocked up a C body drivers side on my BB dart with factory K and it looked at though it would clear with a 2.5" headpipe with a little hammer clearancing. I had also thought of having the manifold to head surface decked on an angle to tuck it in and also a little angle cut on the pipe flange 2 ... but I have 2 sets of stock manifolds so it went no further than to just look.
I had thought of doing it for FAST racing , the top of the manifold LOOKS just like the factory A body manifold and it would have been less restrictive.
