Rex,
I take it the sheath is a Maurice Johnson, tight-stitched, roughback. The fact that the green verdigris from the hone pocket snap is shown and impressioned on the stone would have me to believe it is the original stone.
I cannot say, for certain, without a better look at both sides of the sheath and a close up of the blade stamp, but mid 70's is a more-than-fair date guess (as Rod has stated).
Hope this helps,
Capt. Chris