Hey, I had one of those univoxes! I thought it sounded pretty good.
I (badly) turned mine into a baritone, sort of ... replaced the bridge, replaced the bridge pickup with a duncan P-90 , added some guitar tuners, cut a nut (badly), and strung it standard guitar tuning, E A D G B E but with the E and A an octave down. It was a bitch to play but it sounded pretty cool.
I wonder where the hell that instrument is now? I have no idea! It went missing during a period where I moved 3 times in one year...