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.