The old owner didn't know or realize the balancer issue. That is my bet why it went cheap. He probably thought he screwed the whole thing up beyond a reasonable $$$ fix.
And you can just hear his chevy buddies telling him it's a pile because it shakes like a poor kid having an epileptic seizure.
I know they use those POS carb because it's a dang info-mercial, but, come on. Put a real carb on it and see what happens. I see no reason that thing couldn't have made 470ish with decent ring seal.
I know if I was in that place, first thing I would do is hit both those guys with a torque wrench. it might not help them, but, I would feel much better! LOL :-D