To do a quick check just for getting the rough clearance you can do it through the sparkplug hole, just insert the sloder through the hole and feel it touch the cylinder wall, turn the engine over and remove for measuring. I do this in alignment with the piston pin and do it both directions. It will show if there is sufficient clearance to run a saw but if I am going to set the engine up to run a real close to the line clearance then I do the solder in the four corners setup where the cylinder needs to be put on, tightened down, turned over, cylinder removed and the measurements made from the four pieces of solder.
Pioneerguy600
Pioneerguy600