I’m running a 4.10 gear and the converter is NOS Hurst 11” shotgun street converter that is a 19 spline ,I still have the original 66 transmission in the car so it’s tuff to find a performance converter but it’s stall is 2800 . The car is a slug out of the hole so I have work to do the carb for sure needs attention it’s a 12 second car .