Well I blew $10 at the wrecking yard. After looking at hundreds of water pump pulleys, I brought one home. It looked like a perfect fit but the four bolt mounting hole pattern is off and the center hole had to be enlarged 1/16" to fit the water pump shaft. When I slipped it over the water pump, it was out of alignment with the alternator and dampner pullies about 1/8" (in the wrong direction to shim".
I should have the alternator double pulley next week, then I will see how that lines up with the dampner grooves and go from there.
Take a pulley that you know fits your engine with you, have the people at the yard mark it so there is no doubt that you brought it in with you and use that pulley to compare against others you see.
It seems like you should be able to find new ones pretty easily from Summit or Jegs or some place like that. It won't be for a Y-block but should be able to work, nonetheless.
Another thought, are you running a truck or car pump? You should be able to find pulleys for a car pump pretty easily. A truck pump has a larger shaft and there will be far fewer options but you should be able to enlarge the center hole, as you have done with that other pulley, to fit. You want to be pretty accurate there, though.
On things like that I'll usually set it up in a drill press and use a drill bit that fits the hole to get it lined up and clamped. Then I install the bit which is the size I want and open up the hole.
Its a truck pump. I suspect the donar I tried was off a car. I did take the stock single groove water pump pulley with me and compared them. Perfect groove size comparison. Perfect overall diameter. Perfect inside hub diameter. Shaft hole and mounting holes off, but looked like I could modify them.
The problem was the thickness in the end of the nose cone. The stock pulley had about 1/8" thick metal. The donar was only 1/16" thick metal. When mounted, this throws the alignment off abouot 3/16". Its in the wrong direction to shim. I think that three pulley one was a good option, but I dont want that extra groove sticking out there on the end of my water pump pulley. It will never be used. I have an add on pulley for my double dampner if I ever want power steering, so Im going to keep looking. I see those on Summit and Jegs. Problem is determining the distance between the inside of the nose cone to the center of the pulley grooves. Asking them that is like a major event.
RE the pulleys from Summit, ask the manufacturer, not Summit for that info. The manufacturer usually has it readily available. Better yet, tell them the dimensions you need and see what they can offer then buy it directly from them or from Summit.