The 8 shot frame is only for 8 shot guns. The 6 shot frame is for all calibers of 6 shot. The ejector rod is in the same place on both. It still has to be in the middle.
The barrel mounted ejector rod latch would presumably be .030 too low with an 8 shot barrel on a 6 shot frame, but a lot of the 8 shot guns don't have that. Instead, they have a yoke mounted ball detent to hold the crane at the front.
The hand pushes the same distance for everything. The width of the hand is what determines when it disengages the ratchet. Once it does that, the hand slides on up past the ratchet. You can watch this as it happens with the sideplate off by looking in the back of the hand window. Be sure to take the tension off the mainspring, or just remove it and the hammer.
The cylinder stop is the same for all K,L,N frames.