[fred cook]

If you don't remove the pistons from the cylinders, then you eliminate breaking a ring on the reinstall. Each end of the cylinder can be taped/closed up to allow for external cleaning. Personally, I have removed pistons and cylinders as a unit, but I did not intend to reuse them. Shipping them as an assembly is much more conpact a process. I'll let the next owner do the final disassembly and cleaning, etc at his risk not mine. If one is going to reuse the parts, then the pistons would need to come out for cleaning and measuring.