Some info verified using a DCM scan (http://digitalcomicmuseum.com/)
Originally credited to Bob King, but there is some confusion on Jerry Bails' Who's Who about this name. It is supposed to be pen name for both Bob Montana and Warren King, also spelled Bobby King, but that name is only found in stories drawn by Bernard Klein.
Bob Wood is only credited as writer on Firefly by Who's Who. That must be wrong, as the same art with the grinning faces are found on the cover of Target Comics Vol 2 No3, signed Bob Wood, and you don't need writers to make a cover. So Bob Wood is the artist of these signed Firefly stories.
The artist's signature is on the final panel of the story.
Three spot illustrations, two of them signed M.