I agree with Olderdan as that was my experience back in the day too. Did a lot of carb work back then on SU's, Amals etc. with similar arrangements. The minimal difference from alignment wear in the cylinder will only vary the mix ratio slightly, unless severely garred from 1-800 bad airfilter. I'd try a new set of needle and seats before jumping off that cliff. Another thing I used to find was the cable pull and spring would kant the piston if not all in order also. Never did like the idea of metered air leaks or triple slop to hit a tiny hole dead center.

One thought on your sleeving idea would be to use a solid round bar either epoxied or loctite in and then bore, ream and hone to proper Id. Can't remember if there were side ports in the cylinder though?? Question is: what is the ID supposed to be exactly? Used to have a great machinist guy that would do that with bronze round bar on SU butterflies and line bore and ream the set for me.

Just thoughts. You got a great thread going here!
PJ