I made a couple of my own, no big deal - mostly for relatively wide lens (one was for a 90/8 lens...). They are not suited for ultra fast lens (with very shallow DoF), but are close enough "for Government work"
BTW, you can test the setup yourself: put on the new lens, put it on "T", and, after focussing using the rangefinder, check focus on the ground glas. Easy
It will tell you all you need to know. If the RF and GG do not match, you'll need another (custom-made) cam.