I really need a water pump impeller for a 1952 WG4 6hp twin. I was hoping someone could point me in the right direction to purchase one of these.

Try:

http://store.eastcoastmarineservice.com/product_p/47-24447.htm
or
http://www.chrystine.com/impellers/index.html

Always keep the old impeller for a future core.

Thank you very much.