Going by the drawings, it's interesting to note rifle they are based on, Britishicon and laminate handguards. So that could possibly date these drawings to the early 1970's.

I wonder if this was a design aimed primarily at Civilian users of the rifle, with the hope of selling to the government's?

An effort to incorporate mounting to the receiver as opposed solely to the top cover shows some lateral thinking and perhaps knowledge of the issues with the SUIT mounts?