Even though I tested the lens with some ground glass before deciding on which half of the lensboard to place it, I still felt I should check and possibly tweak if need be.
Grab some ground glass, or makeshift from tracing paper, and put it into an empty film pack mask.
My lens having a T setting made this much easier. Just click and it stays open while I test for focus.
Look through the finder and find something that is far enough away to be considered infinity. Check this against the ground glass.
Do the same with something very close up.
I was very pleased to see that the 127mm lens, being placed onto the front of the lensboard, required no tweaking.
The closer you focus the rangefinder and lens do not agree. But planning for this when shooting is as easy as not framing to the edge and stopping down the lens to at least f8.