A box of compressor parts arrived today from Kam1973, Helping me with this was an act of kindness that I must acknowledge. We meet on "The Garage Journal" forum in this thread.
With these parts I should be able to restore the compressor without resorting to JB Weld to fill the pits in the cylinders.
My next step is to free the piston from my worst cylinder so I can reuse the rod. But now I don't have to worry about saving the cylinder or piston.