The IIB has the greatest clean of any mark series (imho) and the 15" driver only makes it more desireable to me. I think, as memory serves me, that the best thing to do is dial in a great clean, and push it with a great overdrive pedal. I'd suggest a TS808 re-issue or a tubescreamer modded to TS808 specs...Seems to serve the Boog's voice best...
The lead channel is OK for some Santana-esque stuff, but really, I've seen them most often used as a clean amp, pushed....
Great find!!
ax. 8)