Late model pumps are more efficient and have different choices of pump material, and different flow rates per RPM. Long ago I would cut blades off the impeller to reduce resistance and for higher RPM flow. A water pump is set to flow its best around 2500 RPM or so. At speed your car relies on the high flow of air forced into the car. At idle your car needs the pump, and fan to stay cool.
Serp pumps on mid 1980's motors had a standard rotation pump with a serp belt. Unlike the later serp pump reverse rotation.
Look at a mid 80's serp belt setup. If the pump pulley is splined the pump is normal rotation, smooth/reverse. I use a 1986 Marquis 302 in my old Bronco. It has a serp belt normal rotation. NO TENSIONER. I run ALT/PUMP/PWR STEERING & Balancer. Except I got lazy and bent a piece of exhaust pipe to cross under the radiator instead of changing the the bottom outlet to the drivers side.
Maybe one day.
I did run into space problem. I couldn't run the clutch fan, or just the fan w/no clutch. I used a old Ford 4 blade fan. Works great. A clutch fan is farther out from the belt. Without the clutch it hit the belt. The 4 blader was skinny enuff to clear everything.
The only way to tell a pumps rotation (off car) is by the impeller, outsides are the same.
Hope this helps.
Frank