I have a 1973 sub and a 1976 and both of the motors still send the window up and down.
Now, the switches, wiring and other stuff might give you grief, but I don't think I'd give up and switch to a crank window yet.
My guess is the "window motor has failed" is incorrect.
Actually read through this:
http://67-72chevytrucks.com/vboard/s...d.php?t=775471
Do you want to do some trouble-shooting on your existing window set up?
I'm very confident you can get yours to work properly.