what pinion angle?

Like the pic in the moparts link near the bottom with an angle finder, Rosseler Trans, do it that way. Put the angle finder on the output shaft, get angle. The angle of the pinion should be opposite that for a "zero" angle. Roll it down form that point to get what you want.

In a 4 speed SS spring car, I'd go about 5-6 down which still may not be enough, but any further and the U joints don't like the workout.

You can set it using operating angles as well.