Agreed on the 4.10s w/ 35's; may want to also consider inspecting/rebuilding/replacing the factory rear LS (if equipped) while you're at it... same labor once you have the diffs pulled. If not present from the factory, the Detroit TruTrac has some great reviews for both the F&R applications
Re: transmission management, especially re: converter lock/unlock, take a look at the Banks TransCommand. I've run one since my rig was nearly new and have been completely happy with it- locked converter in 3rd & OD, with firm (NOT harsh) shifts.
BBF