capping off heater hoses

Best way is with a threaded plug but installing one in the aluminum water pump is nearly impossible without cracking it . Don't trust those rubber boots that plug the end and are held on with a hose clamp for anything more than a temporary fix. There are water pumps available that have a threaded bore for the heater hose nipple so they are easy to plug off but they're quit a bit more than a stock replacement w/p . I believe they're made by edelbrock.