With those gears, almost every manual tranny is going to have an extremely steep first gear. Except for a 2 speed power glide.
If you really want to street drive this car with a workable overdrive, why not put in a cam that will work well for both. I have a mechanical roller in my big block that pulls 10" a vacuum at idle and will rev to 6800. I can pull it all the way down to 1800 comfortably in 5th gear. IMO that cam is way to big unless it's a RACE CAR.