904: should I switch to 727?

OMG. I need to clean off my boots after reading through all that drivel. Don't touch any TF before 71 or after 78 just to be on the safe side. A 66 doesn't have a rear pump; and you don't want that crap anyway. I would probably tend to keep the 904. What do you mean about the build of the trans when you say that it was a former hole shot car? I'd like to see the guts, but your motor sounds like something a 904 could handle. Thin Red Eagles in the direct drum, Kevlar band; are a couple of cheap upgrades. A cheapo TransGo RV shift kit.