I cut and pasted this from another thread, and I personally recommend:
If you ever can't get new cylinders, or just want some to last near forever, have the old ones stainless steel sleeved. DON'T mess with brass sleeves.
The guy to have stainless sleeve your cylinders is:
Mark "the machinist" Frappier
82 Mountianview St.
Agawam, MA 01001
413-789-4588, or 800-528-5235
You send him your bare, stripped, clean cylinders, and he sends them back with a perfect looking stainless insert.
You will still need to go to NAPA and get rebuild kits, or perhaps Jim Carter sells kits?
Grigg