Cool that in post #20 you finally told us about your car, engine, and accessories. It all matters. Even in the same year the pulleys often varied with power steering (you have?) and perhaps the pump model (Federal or Saginaw in 1973). You have a Federal pump. The Saginaw was more efficient and is easier to get, probably since used on most GM's, plus all I think Mopar used at the end.
Easiest would be to buy a used Saginaw pump w/ brackets on ebay. If the pump is old, turn it in as a core for a rebuilt one. They came on 1980's Mopars too, so perhaps brackets from a small block Volare, Aspen, New Yorker, or such would work. If you want new, Bouichillon sells new brackets for each type pump.
