I recall Guzman's name in relation to TOS, but I don't believe he there very long or the extent of his inf;uence.
He was the Art Director to begin with in 1964. Matt Jefferies was his assistant. But before he long, he decided to go back to his home country and was replaced with Franz Bachelin for a very short time and then Jefferies took over as the head honcho.
All this took place from to the start of filming "The Cage" and MJ was the the main creative force by the time things started to be built.
What I had confused myself about was Guzman's involvement with First Spaceship on Venus.
--Alex