So I've been fixing up a 6x9 Tech III and have encountered similar questions. One thing I have noticed--I have two 180s--both tele-Artons, one ƒ5.5 and one ƒ4. I have found the 5.5 is more-or-less at infinity at the third detent (the III doesn't have flip up stops like the 4x5 technika, but instead has detents drilled on the rail, not sure about the IV.) But the ƒ4 focuses at infinity at the same detent as the 105.
I don't know yet how likely it is to match a similar lens for the rangefinder. I do know that my tele-arton 180mm ƒ4 absolutely doesn't match at all. the ƒ5.5 seems closer, but I haven't had a chance to properly test it. Given the greater depth of field, I suspect the 65mm will have an easier time matching. In the ned, if the lens matches the cam, great, but I don't know that there are many options to adjust. If the infinity stops are like mine, they're not adjustable, if they're like the 4x5 technika, they are adjustable. But other than adjusting the infinity point, the only other adjustment I can see involves a file on the cam.