Was just a thought. There is also a small size tek-lok that has holes spaced 1/2" and 1", and I think the Spyderco G-clip has the same.
As an additional thought, when I designed my UKE, I spaced the sheath-holes 3/4" o.c. for kydex sheaths but figured that someone might make leather sheaths like yours to which the UKE could be mounted as well, to let users switch around their carry style without having to go full kydex
https://www.bladeforums.com/threads/universal-kydex-sheath-extender-uke-2-0.1683794/
Got any on-edge shots so folk can see how thick they are?