finishing up on a gt40p roller 302 swap in a 56 f100 and just about done and ran into this problem.

do they make a thinner pulley?

right now it has a mustang style 50oz HB and v belt pulleys that were supposedly from this truck..

what car/truck would have a pulley that i need? and anyone have one?

 

Well if you were using pulleys from a 56 F100,(no small blocks back then, not until 1962) that was your first mistake. You need a set of pulleys for an "alternator only" accessory drive setup. The crank pulley from a 70's 351 (W, M or C) will have the sheeve that lines up with that waterpump pulley. But since you've spent money on that shiny waterpump, I'd suggest getting a set of shiny aftermarket pulleys instead.

 

Some junkyards have bins of random pulleys. Try to find such a place, bring your measuring tape and verniers and start digging.

 

I think that water pump pulley may be your problem; it looks too deep. See if a v-belt pump pulley from another small block will work.

 

If you don't need the double pulley it makes a better looking installation to get singles.