Thought I would try.....likely not much chance of finding an original one.....the problem is even when you find one it has been messed with and no longer matches the spec sheet. There was a post on the TORC Facebook awhile back that mentioned 650X and 650XS powerhead parts and if people were interested. Maybe some one is interested in getting those parts and I could get a sleeve from them.
TORC Facebook ...
https://www.facebook.com/groups/72034629960/Mark Tribe
We have unearthed a number of 650x andxs parts finger port blocks and standard , not many skinny ring pistons is anyone running them any more if any interest get back but we're in the UK