Ok, well these were made in the 50/60's and maybe closer to an I frame and is a 4 screw side plate. They also came in a .32 but besides the leaf-spring instead of a coil spring and hammer mounted firing pin its nearly identical to my M34 and even uses the same side plate screws ,grips,and the J-frame end-shake washers will fit. I was told when searching for grips for my square but j frame M34 that Pachmyer moved the grip screw location at one point so it wouldn't interfere with the leaf hammer spring of earlier models. Maybe they were referring to center fires though.
When i screw the hammer spring torsion screw all the way in the leaf spring sure looks bent a stressful amount but I will take your word on it.
I see what you are saying on the cylinder gap. I thought the hammer pushing on the cartridge would close the gap but the overriding force of the shell going off will force the cylinder far-most back while firing.
I was going to go for a .007 'forward' gap but will just shim it for a .001-.002 max end-shake like you recommend but is it really that critical like on more powerful center fires that can beat themselves todeath. The .017 cylinder gap doesn't bother me much for what I payed.