It sounds pretty awesome. And it really digs my fuzz pedals.
I think it needs some capacitor work, but as simple as the amp is, that shouldn't be a big deal. It distorts quite a bit. I'm waiting to try it with a bass that... isn't famous for making amps turn into a distorted mess before I do anything.
Welcome to the ‘60s. You should be able to get quite a bit of clean head room before it breaks up. But I’ve never actually heard one that wasn’t run into the huge folded horn 18 so that may be a factor too.