john,
one thing... you do not worry about temp when you break the engine in? if you break an engine in at too low of a temp, you will wear out your liner (sleeve) and loose compression. when the engine heats up, the liner (sleeve) expands. now if you do not heat the liner up enough, the liner will not expand enough and when the piston goes up through it, it will wear the liner. this causes loss of compression.