OD or Non OD 833 behind a slant 6?

If you want to keep the rear stock, I'd look for an early 4 speed.
Has a 3.09 1st gear but NOT overdrive.
If you run a 2.76 with OD you'll never use 4th, might as well leave the 3 speed in it!
And before you do anything verify what rear gear you've got.