Much more difficult to find than even the 85/3.5. I just acquired a Kallo WF rangefinder camera from Japan with the same configuration 35/F2.8 Prominar, that was made for the 140, although built in. This camera differs from the standard Kallo W, in that it has a built in light meter and bottom lever advance. Been looking for one of those for 10+ yrs. I find this lens to be really good, and Dave, you can't have mine for the 140!
I remember back in the day checking out a 35/2.8 Prominar for LTM in the box w/finder on Ebay and I was thinking about spending maybe $300, as I had never seen one. It ended up going for about $1200 and found there were only maybe 100 or so ever made with that mount.
Good luck in your search. It only took me again about 10 yrs to find the 85/3.5 and the 35/2.8 and as I had said before, bought two sets within a very short time and eventually resold one set at a decent profit.
You just never know what'll pop up if you keep looking.
Gary Hill