Slant 6 engine builder in Ca?

Id be upgrading that 7-1/4. No need for Dana 60 for sure but an 8-1/4 or 8-3/4 would be much better if you are adding any "more power" to that engine.
at a minimum Id be looking for a Sure Grip for it to spread the load out to both wheels..... maybe look for another 7-1/4 that has one and if out of a different series of car, swap the guts in. Unless I was adding some kind of overdrive I sure would not be stepping all the way to a 4.10. what ratio in there now?