>>Cotton: Are you certain that the marks on that sleeve isn't there because of uneven temperature in cylinder (hot on the right side causing distortion)?
Let us first assume that a sleeving job can be performed successfully, as they have for generations. But most of those generations had more experience than ours.
The photo shows the outside of a sleeve removed after service.
(Just the fact that it could be removed indicates a poor installation..)
Sorry to use a Chief sleeve for an example, (And I have since edited it to show it right-side-up),
But the carbon indicates a large gap between the sleeve and the casting, or it wouldn't have been able to get in there and cook.
In a solid casting cylinder, the major distortions in service are, as you mentioned, heat-related adjacent to the exhaust's heat-sink finnage, bordered against the cooling of the intake. The lop-sided aspect of flatties is a fact o' life (and frankly, dismisses the usefullness of a top torqueplate..)
A sleeved cylinder faces this as well, but also must contend with friction and hydraulic forces of the piston skirt against a spring-within-a-spring spigot at the bottom. A bottom torqueplate will allow the bore to be fitted while 'sprung' to the fastener's stress at least.
Chiefs do not even have an extended spigot, no more than the scallop at the bottom, yet the example in the photo shows the heat was contained half-way up the piston's travel. U's have very large spigots that pucker both inward and outward from the base nut's torque alone.
Whether the fuse is lit from the top by unusual combustion (advanced timing, vacuum leak, etc.), or at the bottom by a rubbing skirt, temperatures quickly rise to burn valves, stick pistons, warp heads, etc.
But with simple techniques, these problems can be minimized: Reduce the insulating gap between sleeve and casting by finish-honing,... and pre-distort the cylinder base with a torqueplate when finish-honed.