Thanks so much guys, for all your suggestions. After visiting the web-sites of the businesses you suggested, I found none of these mounts remotely resemble the mounts on the original Slotterbeck rifles I've examined. It seems, as usual, old Charlie set his own course in the area of scope mounts, just like he did in his gun building. The scope mounts he used, didn't use the spring tension full floating system seen on early cartridge rifles, and target guns of the early twentieth century. His mounts utilized a thumb wheel elevator on a shaft anchored in the tang of the gun, and a cross screw activated windage adjustment on the front mount. I fear I am doomed to make my own mounts on this one. I found a nice set of 3/4" steel rings on an old air gun scope, somebody gave me years ago, after their kid broke it. Those rings, along with an extra tang I bought for the rifle, so I had one to experiment with, will be my starting point. Wish me luck.
Hungry Horse