"There was a period scope mount that attached to the receiver sight screw holes and either the front receiver ring holes or to a base in the rear sight dovetail. A Stith Instal It Yourself mount, I believe."
Bingo! I couldn't remember Stith. I was sitting here going S.... S.... S... damn it, I know the name!
Yes, Stith made mounts that used the side holes.
They worked, but they weren't the most stable.
On the plus side, you won't pay a lot for one of these mounts. I've seen them go for $40 and $50, and they seem to be relatively common.
The the minus side, they have not been made for years, and you'll have to have patience in finding one.
Check E-Bay, Gunbroker, and Auction Arms.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.