I see. Remember that contraption.
You might get the lens to focus to infinity with the proper helicoid. Putting a genuine Z mount on the rear will shorten the extension dramatically too. I purchased a handful of spare mounts and have used them for various adapters for my special 'exotics'. Still not satisfied with the helicoid for the 100/1.6 as it currently only will focus to about 3 m, but I know the underlying reason and the issue can be solved. All in due time.