My 69 510 had a drum clutch type water pump. If yours is original, yours might be also. Bad news though, you'll never find those parts. If you have that type in your car, I'd just buy a pump from rockauto. And you'll need a new fan to go with it. Aisin is the OEM for toyota water pumps, and they make pumps for the L motor. It's a quality pump with a cast impeller. If you have a viscus clutch or no clutch at all, you'll be able to find a replacement pretty easy and then you can just reuse your existing fan.
If you have the drum clutch type and you'd like to keep it, you can. There are a few companies that rebuild water pumps, but it won't be cheap.