383 engine with 4B/Carb with 323 gearing in the rear would you keep the 727 or would you select after market auto tranny with over-drive for high-way cruising.
The only bolt-in aftermarket OD automatic has a very low first gear, which means the car will kind of “fall on its face” on the 1-2 shift, but the OD is sweet, as is the lockup converter. (shiftsst.com )
3.23:1 cogs aren’t at all bad for cruising, 2.94 is even better.
It comes down to this: You pays your money and you takes your choice!