Thanks so much for that, Jim!

That's exactly it. The Custom Hunter 2.

I have discovered since my initial posting that sometime prior to the publication of the 1979 catalogue, Schrade introduced an improvement to the steel and subsequent knives were marked "SCHRADE+".
So I had already (potentially) reduced the likely window by one year!

Now off to peruse the other catalogues on the Collectors of Schrades website.

If I win Lotto an original Loveless drop will be an early purchase!

Edit: I note that the 1978 flyer for the CH2 in the link above refers to the new Schrade+ steel, but apparently the initial knives were not so-marked, perhaps not until 1979?