I've got a 77 crew with NP445 and married 203. I've got 4.56 gears and am seriously considering going to 3.54. but you have the advantage of divorce case.

I ran 900*16 for a year, not enough to make up the gears and rubbed the fenders.

If you insist on stick, I'd go 4500, if you're ok with auto run the 46rh. Both are fairly easy swaps.