Rocky Cycles do a .75 o/s kit. Not sure if you can get the rings for them separately. They come up on Ebay pretty regularly. Not sure what they are like, mine is in transit from the US as we speak. I think it is Vintage Suzuki that can get Wiseco kits made in a variety of sizes too.
I am learning the art of RM465 love too, doing up an X model, it appears to be a bit of an orphan, at least your Z parts cross reference with RM500 parts as well which adds to the possibilities.
Adam