I think you are missing the point to such an upgrade. It is not only locking the spindle, but the addition of better bearings, and motors for additional speed would be a super benefit as well.
I had a round column RF30 style machine sitting here for years not being used. It was too large to use as our go to drill press. We have several different kinds and sizes of those already anyway. We keep them setup for the jobs each does.
I initially planned on cncing it, but the major drawbacks besides the round column was the quill spindle and speed. I did get a good deal on it, so about half price from Harbor Freight. I sold it finally for half of that to the guy that bought my home made 80/20 mill and lathe. Both in working condition.
All told, I recouped about a tenth of the money that I had in those, but the mill and lathe had already surpassed the ROI at least two fold.
Sorry for the side track. You mentioned in another thread that no one breaks the mold. I do not recall seeing very many guys on here solve the quill issue on these, so I think this was a very cool project and obviously worth the effort.