I'm having a cylinder rebored to 66.5mm and Wiseco has the below two piston options, but they've told me neither is a direct fit for this year/model and that they don't offer other options. Disappointing because they do offer all sorts of options for 1978 and up.

I bit the bullet and bought a OEM/NOS one off ebay, but that's way to expensive to do more than once so Enduronut if you see this do you have any advice on other piston producers? Your name came up in multiple related posts. Thanks!