904: should I switch to 727?

If you want to learn all about your transmission and ways to toughen it up you should buy this book, it's excellent and comes highly recommended by several FABOians.

View attachment 1716042210 SA Design SA394 SA Design Chrysler Torqueflite A-904 & A-727 Transmissions: How to Rebuild | Summit Racing
Yup, probably the best book out there.