Joe,

I think the bottom-line is that they only make tanks for 60-63 wagons.

By looking at the picture Jeff posted of his you should be able to get one of those and with very little effort get it to go into your '65 wagon by making sure the tank is mounted to the drivers side so the filler hose connects and the fuel sender being on the left side rather than facing forward means the fuel hose connection to the line running forward to the engine is a bit longer to reach the side-mounted sending location. I am guessing a 65 sender fits the 60-63 tank, since they appear to be about the same thickness of tank and the sender is up high like my sender was.

You may need to put something next to the tank on the passenger side to take up some slack in the straps so they will tighten up since the 60-63 tank is a bit narrower. You could probably use some plastic PVC pipe or something. It would probably be nothing bigger than a 1.5" diameter piece the length of the tank. Who knows, it may not need anything.

So maybe, what you could do is to take some pictures of what you have and from those we can brainstorm the actual best thing to do.