That's a good one man! Funny part is that I also own a BH-420

! Anyway, I did a little research on this old head. It's a all tube head and from what little I've read here and on Harmony Central, they have great tone and are bullet-proof. Here is a little info:
Earth Sound Research B-2000 SuperBass Head:
(from Harmony Central)
It has 4 6L6 and 3 12AT7 tubes. It is a copy of the Marshall Superbass, which was a copy of the Fender Bassman. By changing four capacitors and 3 resistors it converts into a copy of the Marshall Superlead. It's all point-to-point hand wired, one channel, two inputs, one of which is labeled Super, and there's a switch labeled "Deep", which is a bass boost.
(from fellow TBer "Throbbinnut" on another thread)
I love the Superbass B2000. I think your talking about the tube model, right? Copy of a Bassman 100. It's got (4) 6L6GC's, so it's only 100 Watts. The "2" in 2000 refers to the 2 channels - Regular and Super. I've rebuilt a couple for folks and they love them. They're the perfect cheap tube head that you can use as a workhorse and you don't have to worry about them falling out of the back of a truck, like you said. For $250 with a cabinet, I'd go for it. Best thing to do is get the power supply capacitors replaced, and possible retube it if need be. So for another $100 it'll last another 30 years!
So it looks like I got a good used bass and an all tube head in working condition for $200 + shipping. Not a bad deal. I'll prob sell the bass and keep the head...