I could sell you the 4th axis kit that goes with the Taig Mills we sell. It consists of a solidly-built rotary table with a 72-1 planetary gear that accepts a range of chucks, has a NEMA 23-frame motor attached, and comes with an adjustable tailstock. It could certainly handle cylinders the size you mention, assuming there's room on the bed of your MPCNC and a spare driver channel to run the motor.