Agreed!!! The driveshaft needs work either way, with the small bolt pattern you'll be able to bolt your wheels back on, and it holds its value! You can always big bolt it, and easy gear changes are about an hour to do!!
Good point about the bolt pattern. For me the main reason for swapping to the 8 1/4 in my '74 was to get the big bolt pattern since I wanted to put '73-'76 factory disk brakes on the front. But in '72 you would have had SBP even with disk brakes. If it were my car I'd probably not want to change that.