These cylinders are per Bob Reedy's design except that the bore has been increased from 1-5/8" to 1-3/4". Reason was that Bob's boiler ran at 125 psi and my copper boiler will be limited to 100 psi. The increase in diameter should result in the same power being developed. This was probably not necessary, but we will see how it performs once it is steaming.
The use of a bronze bushing (SAE660) as a sleeve also works well with PTFE (Teflon®) piston rings because the inside of the bore is very smooth.
These piston rings were acquired from WW Grainger Company. They are meant for use in air compressors and were inexpensive. They came with a Buna o-ring backer which must be changed to a same size Viton o-ring backer for steam service.
Teflon slide valves: we have a 3/4" scale locomotive with a solid Teflon slide valve built by Bill Van Brocklin. This engine runs very well with very sharp valve events. The slide valves below are made from Teflon with 25% carbon.