There is a very well thought out and nicely explained timing tuning plan posted in this thread by jbc426 which entails using manifold vacuum which is supposed to enhance cruise mileage and part throttle torque. He explains that there is a symbiosis to initial, total, curve rate, vac can choice and settings which would likely require a lot of patience, bit of fab and a good level of skill. I am giving it a solid effort to duplicate his recommendations in the near future.
http://www.forabodiesonly.com/mopar/showthread.php?t=278252