An adjustable band clamp is a good tool to compress the rings. If the width of the band clamp will not cover all three rings, cut a strip of thin metal to place inside the band to insure each ring will be correctly compressed. Tighten the band completely and then loosen it slightly to allow it to slid down the shirt of the piston as the cylinder is pushed down. This band clamp will not occupy much space and can easily be removed once the cylinder is down over the rings. A rubber hammer may be needed to bump the cylinder down past the piston rings.

Insert all four of the cylinder head bolts and leave them slightly loose. Then rotate the crankshaft several turns. This step will allow the cylinder to move and find its center position relative to the piston. Then tighten each cylinder bolt. Make a second pass to each of the bolts to verify that they are securely tightened.