Bob, I am dealing with the exact same issue.
I purchased a project truck with no engine or pulleys. I had a power steering bracket and pump. And the truck came with the alternator bracket and short water pump. So i found a matched set of crank/waterpump pullies from a board member.
I installed everything today and found the same problem as you did. Everything lines up with the crank pulley except for the water pump pulley. I found my water pump measure 5.75" from mounting to hub face, same problem as yours.
I plan to see if i can press the hub on to the 5 5/8" measurement.
This article might help.
http://www.corvettemagazine.com/engi...p-rebuild.html
Any chance you could share the part number on your power steering pump pulley?