I could have saved you the effort since it was my first mountain bike -- 1986 dark green Antelope 850. The original mountain bikes were fully rigid so it didn't "appear to be a mountain bike," it was one. I can go get it out of my mother's garage if you feel the need to see it in person.
Thank goodness the spiffy roller cam brake they came with died a quick death. Happy hour design brilliance, let's put the brake underneath the chainstays so it will collect even more mud.
Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.