I think you're on the right track with that Carvin BX1200 head. I looked at a used one at a Daddy's Junky Music a couple months ago that was basically in new condition and I was really impressed by the bang for the buck in this piece of gear. Lots of power, lots of EQ'ing... LOTS! I would have grabbed it right away, but I've settled in with a preamp/power amp layout that I'm extremely happy with these days.
A Carvin cab might be a good match for that head, but another great value around these days is Avatar. You can check out some of our pals' experiences with their stuff here or look up their website. The used market is full of really good stuff too, but you never know when you're going to stumble across "that" fantastic deal. I like dealing with Daddy's because they'll back their used gear for a short period after you buy it and you can also pay for extended warranties, plus they take trades.