SM,
I remember a number of low power long eye relief scopes that mounted ahead of the receiver, usually using the rear sight dovetail, from that era. Leupold offered it in their Detacho-Mount series, as did Bushnell with the Phantom. I've never seen one (1) mounted that far forward, that I can recall. I would seem to be a location just begging to be bumped out of zero.
Sincerely,
Bearrr264