Been fighting some of the same issues with mine on the 360. I have a pretty radical cam which I don't know the specs on. They need more fuel at idle, I am 2 turns out on the outboard needles and it's still a bit lean. Runs much better and tamed the idle with more fuel. With the jettable plates you might be able to circumvent some of that.
Read the old article about halfway down this page:
http://www.mopar1.us/6barreltips.htmlIt's 7 pages and really details the theory of operation and good tuning tips.
