I have 2 and one has about 6 oz. of fuel through it and the other has not seen any. Saved them for a twin project but lent the plans out and havn't seen them since.
Both are ringed and I believe a regular ring would work. If you can find a dyke's it would also work. The problem would be how much wear is in the cylinder or the piston. You could maybe get away with a ring replacement. If you have a piston then I would install it to try. Remember there is not a great amount of compression with the ring setup especially dry.
For the buttons on the wrist pin I would use some teflon or something like that. They said they where Teflon back in the days so it would not hurt to try. I would not go without them as I have seen a cylinder scored.
John