I have a circa 2000 Skip Hujsak frame. It bears some similarities with this bike but other differences make me think it isn't his.
First, I believe he did work in California under Eisentraut, so a 1970s or early 80s frame of his there isn't unlikely. Second, the bottom bracket, fork, and lugs in general are more or less the same. When I met him, he was using mostly Reynolds tubes. Also the rear triangle is not similar. He liked an extremely short chain stay. I don't believe you could fit anything bigger than a 25mm tire on my Hujsak racing bike. Also, where the seat stay meets the seat tube at the clamp is very different. His design has thev seat stay as part of the clamp like an old Basso Loto. Sorry, my frame is in storage or I'd leave a motorcycle. My guess is it isn't a Hujsak unless it's a very early one.