Correct Water Pump for Early 273 w/ AC

I measured the pulleys. Crank pulley is approx. 7 3/8". Water pump pulley is approx 5 3/4". That gives a ratio of 1.28:1. So at least that checks out.

Rock Auto will take back the water pump, and Oreilly's has a pump in stock that might be right. At least I'll be able to bench compare them and make sure what I'm getting is right.