When I installed a '66 Saginaw 3 speed in my '50, I had to do some creative modifications to account for the different location of the shifter arms on the transmission.
It resulted in creating a geometry issue, which at first, I was not happy with. It caused the throw of the 1-2 shift to be short throw, while the 3-R remained correct.
It created no issues in shifting, and in fact helped me to better determine when I was in first gear rather than third gear at a stop light. So I called it good enough, maybe even better than stock.
Carl