My 383 is weak!?

A couple thoughts: First would be to make sure it's hitting on all 8, and that each cylinder is healthy with a compression check. If it's healthy, ignition would be next on my list. I think Mopars RV grind is only around .430" lift, which comes in at a bit less if using the stock rockers, and will fall flat really quick. 383's are actually not alot of fun to get compression out of, but if it has flat top, no valve relief pistons, you should be around 9.0 to 1, which is OK for what you are doing.
I didn't see mention of an intake, so I will assume stock? If so I really like the Performer RPM. The regular Performer is OK, but unless you get one cheap, it's just too close to a stocker for me. I would do the RPM, go to a 750 carb, and try at least the stock Magnum cam grind. I didn't see mention of converter either, and if it's too tight, you won't be into your power band at all at a launch. at least an 11" converter would help. A little more gear would be good, 3.23's maybe considering your driving requirements.
Oh, and there is really no such thing as "440 heads" They may have come off a 440, but Chrysler generally used them on the full range of vehicles in a particular year. For instance, many made a big deal out of the "906" cylinder heads, because HP 440's had them. Well so does my '68 Newport with a 383 2 bbl. Good luck.