The place where I've seen the clearance issue is when using the aluminum water pump on an A body that originally came with a cast iron water pump and then adding the viscous fan. The MP clucth fan setup is too long to fit between the radiator & pump because the snout of the aluminum pump is longer than the one on the cast iron pump used on the earlier cars. That's where you need the Jaguar clutch. If you use the stock water pump for the year of the car you're working on you shouldn't have any clearance problem.