I've been doing this for a long time and I've found 3 engines that I couldn't hand start and wouldn't turn over with starter. Two were Tower .75s. They were so darn tight, I thought I would harm the engine by turning it over by hand. The third was an Evolution .36. It was so tight that I took it off the plane, a Plug-N-Play profile from Hangar 9, was it a Patriot?? I'm not sure. I thought I was going to tear the nose off. It would not flip it was so tight. Of course I put oil in them and also fuel, but the cold fit was so tight that it was wiping or squeezing the oil out.

In all 3 cases, mounting on a test bench and heating with a heat gun opened up the sleeve and allowed them to be started. After a couple of runs, I could hand flip and start them easily.

As for heating with a heat gun, I don't see the down side. As soon as the engine starts, assuming it isn't totally rich, the sleeve heats opens up to running clearance. This is the design of ABC type engines with brass sleeves and tapered bores. It would appear to me that cranking them over with a high torque started where you go past the "crunch" many times would do more damage than heating the cylinder to cause it to open slightly. I can't see how heating causes any damage.