I'd like to hear some more rhythm playing too, but in the 1979 vid I dig that bend you hold out and let scream. That alone tells me a lot about the overall sound/capabilities of the amp. Well done!
I've never tried it (two overdrives) but there's at least a couple guys between here and the Guitar Gear forum that double boost. I remember hearing a few clips of a Henning Cherry Bomb with two overdrives that sounded pretty sweet.