Oh, I won't give up.
I love to dig, too, but mostly so far I've been digging for Christmas Carols. But a new baby in the house brings back a desire for songs that woke the imagination during childhood.
1971 sounds about the right time frame for the edition. Our elementary school was built new in 1969. We used the whole series of what ever edition it was (I remember them sitting uniformly on the shelf with their color-coded binding) in a school designed for K-6. My sister was in the first classes ever held there and I followed about 3 years later using the same materials and singing the same songs.
I'll definitely look into the 1971 edition of Making Music Your Own. If I can get it through interlibrary loan or inexpensively second-hand, it may be useful to have even just to start a collection of music resources for children's songs.