That's what I was thinking.
The owner's manual and the box look quite similar to the stuff that came with my Gold Cup, in 1980, but the price is very similar to what I paid for my Ace Conversion top-half, in about 1983 - 225 if my memory is right. So that would make the entire lower half of the gun only be 40 bucks. Right in that same time I bought an AMT frame, to build a dedicated 22 1911, using a GI parts kit, and the frame alone was 60.
Had to be the 70s, I'm guessing.