Seems as though I need to replace the water pump on my 55 'Bird and am considering the high output unit available from various suppliers.  My concern is how much additional drag does it add.  I'm already running the alternator and AC on that belt and am worried I might end up putting too much load on the belt, or have to tension the belt so much it would be hard on the bearings.  Any thoughts or experience would help me make the decision.  
   The reason for the high output is heating problems at idle and some when climbing hills.  I have replaced the radiator with an aluminum one, tried various thermostats, larger fan, and a baffle.  
Thanks,
Don