Framed BW 60's Art Photo Print, authentic only one

Framed black and white photo of two individuals sleeping in the back of a Volkswagen van on the beach. "Bob" id written on the back of the van and there seems to be a pillow with the words authentic "Happiness is slee..." The pencil written signature of "mushack" is written bottom right.
This is a personal family photograph, the only copy known a this estate.
Framed in a thin black wood frame. matted with an cream tone , eggshell textured matte.
Professionally framed as the back has a framing center stamp and is read for hanging.
Total measurement is 16&1/2" x 14&1/2". The black and white photo itself is 7&1/2" x 9&1/4th.