merry christmas to all, and to all this question. i have a big block that has a 3 groove water pump pullet, the outermost groove is smaller than the other 2 grooves and runs the power steering pump, will converting to a 2 groove wp pulley and running the ps pump off of the larger diameter crank pulley foul up my original style power steering pump.

Not sure if what year yours is, or if the pulley are stock, but I'll assume 1966...

But NO, 1966 (and I think most years) ran the Power steering ONLY off the front of the crank(third groove)... The P/S belt did NOT go on the waterpump pulley at all...

The smaller third groove water pump pulley is usually for the smog pump (I think for most applications)... And I think that belt only used the WP pulley (and NOT the crank pulley)...