Regarding the transmission issue, I'd be inclined to contact these guys:

http://www.transmissioncenter.net/

Even though they don't "list" the 4L30E, if there's ANY way possible to beef it up, these are the guys to do it! Even though I have ZERO problems w/my VX engine so far, I'm still "all in" on this one! Make it hap'n, Cap'n!