Correct Water Pump for Early 273 w/ AC

I found this press release for 1965 model year factory ac.

http://www.foundationpc.com/press/press65c.html#components

Of note is this section:
View attachment AC Cooling Specs.jpg

The water pump that came with my car has a 3.5" impeller with 6 blades. The new Gates 42553 water pump has a 4.1" impeller with 8 blades.

Looks like the AC cars got a smaller impeller, but also different pulleys so it spins faster. Now I have to measure my pulleys to make sure I have the right ratio? My recollection is that the fan pulley is smaller than the crank pulley. I'll measure them tomorrow.