Glad your getting it sorted
The M952 comes in bottom swing too, i have them on a couple of my bikes, both 31.8 clamps, no shims. I guess shimmed ones are good if you are swapping from bike to bike. M952/3 are both the same, only difference is M953 uses a Reverse pull rear mech, both 9spd. Same as M950/1 are both same apart from M951 uses Reverse pull rear, both 8spd.
The 31.8 top pull mechs are harder to find as they are a common size but if your patient one will come along. Place an ad in the wanted section. Saying that, if your swapping then you should both be ok.
One thing about the fit though, the size difference between clamps is very obvious, if you tried to put the smaller size on you wouldnt be able to get the clamp around the tube, the larger size clamp will close fully and still be very loose. If the clamp goes around and fits the contour of the tube, but you cant quite get the bolt in, then it is probably the paint is too thick.
Mark