Best next upgrade?

No, sorry not directed at you. I was just pointing out that one of the weakest links despite lots of mods is still waiting to break lol.
Not sure if that was directed at me but running the 7 1/4" was temporary, after a few years I had the money to rebuild and swap in a 1967 B-body 8 3/4" which is still in the car now. Also my ultimate goals with my car were quite a bit more race-oriented than the O.P.