I bought one of the left handed Acu-Sport Thumbhole rifles. I you look at the cartridge rifle sight in a picture, you will see what I mean about the fold down(I am sure you probably already know). I am pretty sure the fold down would fit the D&T holes in the barrel. I am sure I have a sight laying around, and could measure it if you want. I did not care for the fiber optics.

I think you will find that the Warne will give you more length-which will give you more adjustment with your scope. I will try to get a couple of pictures this afternoon for you. I have tried the Leupold's, and they were just too short. Tom.