I wouldn't put a lot of faith in the lens markings versus real world measurements. The real test for closer focusing on a rangefinder is film plane compared to rangefinder, ignoring the scale markings all in all. So select a target, get it in focus on film plane, then adjust rangefinder to get it in focus.
The best measurement for infinity would be a distant object. 150 feet or more is fine, given the nature of the CL rangefinder system, patch size, etc. I trust that Leica or Minolta will set a lens for a good infinity setting (and yes, this can go off and need to be adjusted, but if you are up for that you probably don't need forums like this).
And yes, it is possible to have the two points, close/film plane, and distant/rangefinder not agree. At that point you need a factory level manual to make adjustments in the throw of the rangefinder cam and such.
Recommended solution: get infinity lined up and vertical lined up (be prepared to have to go back and forth as changing one often changes the other). Then go shoot for a while. If you want razor thin focus at 4 feet at f/1.4, I'd suggst that you are using the wrong camera. Relax and play to its strength- 35mm grain, speed, nimbleness, nice out of focus with that 40mm lens. Most times you will not notice 2 inches front or back focus.