I have a couple old Stevens scopes that either mount in dovetails with two screws that expand the dovetail scope mount to tighten into the barrel dovetail, or in other cases have bases that screw directly to the barrel like a target base for scopes attaches.
Stevens early on offered several style mounts, and during that time none of their scopes had a Pope rail. They all used a v notch in the front ring, and a pin in the barrel to index them.
One of mine is a very long 32" full length, and the other is a mid length around 26" if I recall correctly.

I have a Stevens 368 scope that is on a late model 44 with a full round barrel, that has a micrometer rear mount where the front and rear mounts are on sleeves that screw directly to the barrel. I've always assumed that the mounts were customized, but I am not sure. They are Stevens mounts, that I  am positive of.