Re Chrome a sleeve
Hi Jack - I would be very worried about trying to machine off the remaining nickel deposit in a lathe, although you could use internal grinding, using a tool post grinder, if you can get the liner really accurately centered and square, using only the lightest possible chuck jaw pressure, since the chuck will tend to distort the liner a lot. I would be inclined to just hone the remaining plate off with a drill press turning the hone, while hand-holding the liner. It might be possible to strip it with 50% nitric acid, but you may get too much attack on the brass. Honing two-stroke engine cylinders is always a problem, since the hone tends to cut too heavily around the ports, but very light honing pressure, and taking your time, helps here.