383 and 400 are not the same kind of engine: a 400 is a torquey engine, originally designed for the heavy cars of the mid '70s, no performance aspect to it; the 383 is a "hot rodder invention" for performance. So, what do you want? A low-end torque engine for cruising? The 400 is great, although they are getting to find and a regular 350 will do the job just fine. If you want to race, burn rubber, and such, build a 383.
