The reverse rotation pump is for serpentine belt systems (because of the way the belt wraps around the water pump pulley), and i'm not sure of any physical differences. If you use a V-belt and pulleys you shouldn't have a problem. the serpentine belt rotates flat side against the pump whereas the V-belt is grooved side. If you use V-belts and a standard rotation pump you should be ok, and vice versa, but i don't know if a reverse rotation pump will work on an older cover. I think also that 302 covers and 351 covers are basically the same so you might be able to use your stock HO 302 cover on your '69 block if you want to use a reverse rotation pump and serpentine belt. Good luck, hope this helped.
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'84 Mustang 5.0 LX
My car