Re: End gap, ring, cylinder (photos 54 twin)
It looks like you are measuring correctly. By "looks like" I mean if you used a piston to square up the ring in the bore. I wonder if you really even have a problem. If I recall correctly, you said you had to thunk on the piston with a dowel or something to move it. That is not abnormal, depending on just how hard you have to thunk it. Judgement call. Furthermore, it appears that you did not move your hone in and out fast enough and have more or less circular hone marks, rather than a crosshatch. That will make the rings slide harder.
I'd do another light re-hone to get more crosshatch, and go ahead and put it together. It will slide easier when it breaks in a bit.. After all, that's what a break-in period is for.
EDIT: I do see another possible problem. It appears your new rings are wider (depth-wise) than the old ones. Make sure the grooves in the piston are deep enough for those wider rings. Also make sure there is no carbon in the bottom of the ring grooves, that would prevent the rings from going deep enough in the groove. With the piston and rings installed in the cylinder, you should be able to move the crown of the piston sideways a bit. If it is jam-up tight and won't move sideways, you have a ring depth problem. Actually, those pistons are tapered and normally have an almost alarming amount of lateral play at the head end.
