water pump and pulley selection

On my 78 fury, 318 factory AC car, I replaced the original wp in the low-40k mile range due to age and just preventive maintenance. This was back around 2011-12ish. Only did so because it was the original at over 30 years old.
That original was an 8 vane pump, parts store sold me a 6 vane. Ever since I put that 6 vane pump on I started having problems running hot. It never had with the 8 vane. I'd taken the radiator out a couple of times, and sent it in for flush/rodding out whatever it needed. It came back fine each time.
I ended up putting a flow kooler pump on and a 3 row champion radiator for good measure. It now runs cool. Almost too much so.
And I remember them saying that the 8 vane was the "with ac" version but couldn't get one at the time. Which agrees with what I took off originally.