Piston ring compressor

[tck]

I have an MK engine in situe (its too heavy for me with barrels on) and I am fitting new JE pistons (two compression & lower oil ring) I have a temporary  solid base  plate inserted under the piston  so its sitting square but I think a good self clamping ring compressor would be a help, the trouble is none I have will effectively go down to the piston diameter. Is there a compressor any one can recommend.?
My normal method on an upright engine is to ease the rings in an allowing gravity to drop the barrel so I havent often used a ring compressor when I have its just been a strip of steel strapping however when horizontal barrels are concerned I dont have 3 hands
I have in the past notably on a BMW part fitted the piston to the barrel  on the bench leaving the gudgeon (wrist pin) uncovered and then fitted the assembly to the con rod however that would still leave the oil ring to sort possibly not a problem .. comments?

[eddie]

You could use a strip of mild steel sheet rolled to suit the piston diameter, then turn the ends out so that it can be squeezed up with a pair of pliers. Once the barrel is slid over the upper rings, the engine can be turned to TDC and the flywheel jammed with a small wooden wedge against the inside of the bellhousing. The ring clamp can then be squeezed up again on the bottom ring. As the barrel is pushed further on to the piston, the clamp will have room to slide off the bottom of the piston.

  Regards,
                Eddie.