You shouldn't have to use any sealant. Just make sure both surfaces are clean and free of any old gasket material and torque the pump per specs and it should be fine. I've never had the need to use any RTV when installing pumps on the case.
Al has you covered, sealant can find its way into oil passages and cause problems. Be aware there are different torques for paper or plastic gaskets, the paper gaskets tend to give you better pressure
The paper ones don't leak as bad either. Make sure you have FREE rotation of the pump after torquing or it WILL shear 1 of the 3 keys. tourbox
Thanks for the replies. Pump was worn around one gear after torquing gear in case didnt turn freely,time for new pump. Any preferences for 79 shovelhead?
High Performance Oil Pump Bodies for 1973 to 1991 Harley Davidson Motorcycles Have a look here, you can buy new bodies with out having to buy the whole pump