I agree with you, heads is a big part and I'm not seeing a good selection of aftermarket for it.
I noted that the intake and exhaust run right alongside eachother, and the intake pipes arent equal. I'd suggest doing this
http://www.forabodiesonly.com/mopar/showthread.php?t=81323
Webbers/Hilborn -- individual carbs for each. If there was a way to make the intake and exhaust on opposite sides of the head I feel there would be some good gains to be had as the fuel would run cooler and wouldn't be vaporized/scorched by the time it makes it into the head.
I also read some stuff on mopar muscle awhile ago about the rotating assembly being heavy and pistons being rather tall allowing you to shave some off, and lessen the deck height a little raising the compression up.