It would probably be a lot easier finding a 383 than a 440 at this point. Most 440's have been plucked from the salvage yards. Chrysler sells new castings for RB (440/426) and Hemi engines. The trick thing (and far more expensive) would be Chrysler's 528 crate motor. As for 440 heads, from '68 on, the heads on a 383 and 440 are the same. The '67 440 heads have small combustion chambers, but are really hard to find.

Good luck!