We cannot tell you what lengthening you can tolerate without mockups, and even then you cannot know for sure because of lens distortion
Also tape measurements are inaccurate. You need xray to have precise numbers, then it makes sense to make calculations
For Arm lengthening unfortunately there are few cosmetic cases so we have little clue as to what could happen long term
I know Apo did it, and I know Betz and Donghoon do it (although it is pretty costly). Dr. Assayag also mentioned once that he has done it on a patient and I think dr Solomin does it as well
