Bent Water Pump Pulley ?
 

Am currently helping my brother-in-law get his '57 Chevy 4 door wagon up and running after setting a few years. He just recently retired and now has the time and hopefully the $$ to get back into it. Just as a precaution he decided to change out the water pump and the rebuilt casting is a bit differant from the previous one. Mounted up fine but when installing the single groove fan pulley found it rubs the water pump body. Did not do it on the old pump but as mentiioned the cast body was differant. Not continuously, as you turn the pulley you can see the outer groove edge rub and then clear as pulley turns. Since he is trying to keep the wagon close to orginal, (bought it from the original owner) would like to keep the current single groove pulley. Is it at all possible to straighten the pulley enough that it can safely be used and just how would you go about that?

I would try a different water pump. If he had no rubbing with same pully but different pump before, then I dont think its the pully.