At the time of the First Scout Rifle Conference, in 1983, there was no intermediate eye relief scope in production that met the needs of the conference. Cooper's first Scout was an out-of-production Remington 600 fitted with an out-of-production Leupold M8-2x that was brought to market for use on the pre-Angle Eject Winchester 94.
During the 1960s, several scope companies brought intermediate eye relief scopes and mounts to market for the venerable 30-30. Bushnell offered a forward mount that utilized the rear sight dovetail for their Phantom pistol scope.
Redfield offered their M-294 forward mount with integral rings and 2x scope.
And Leupold offered a forward mount and Detacho Rings for their M8 series.
Both the Redfield and the Leupold offerings incorporated backup iron sights into the mount.
Redfield recognized the superiority of the Leupold design and replaced the M-294 with a separate base, rings and FrontIER [intermediate eye relief] scopes a few years later. In fact, Redfield's base, rings & FrontIER scope was offered for the Remington 600/660 series of rifles by 1968.
The forward mounted optic never caught on in the 1960s and 70s and the various components were dropped from production over time. Leupold redesigned their M8 series exclusively for handguns at some point in the late 70s or early 80s. I haven't been able to pin down exactly when this change took place. However, I have discovered that Leupold did not include an alpha character in their serial numbers prior to 1976. If you are looking at an older Leupold M8 and the serial number is composed completely of numerical characters, it is a true intermediate eye relief unit. Assuming that the 1976 introduction of serial numbers beginning with a letter began with the letter A and that the letter changed with each years production, we have a rough framework for judging age, and thereby, eye relief on the old M8s.
Shortly after the 1983 Scout Rifle Conference, Burris began offering a Scout Scope in 2.75 and 1x variations.
And, of course, Leupold currently offers their outstanding 2.5x Scout Scope.