Got the right info I think. Need a pully from a 340 motor with the federal thompson pump 3/8" press on, about the same years 70 - 72 alum water pump none a/c.
i just changed mine out to a saginaw pump. mine was bolted to a late model magnum 360,no a/c. don't know if that will help you. call bouchillon performance,they are pretty sharpe on the pulley info.