[SFfiredog]

A standard rotation water pump turns clock-wise looking at the front of the engine a reverse rotation pump turns counter-clockwise standing in front of the engine.
Your dilema is which water pump is on your engine; is it standard or reverse rotation. 351s can come both ways.
It will seriously effect how your engine cools if you have the water pump turning the wrong direction.
The two pumps usuallt have a different bolt spacing on the 4 pulley bolts.
I don't remember which is which; I'd have to look when I get home tonight.
HTH,
Mike