Thanks (mostly) for the (real) replies!
Hunter was closest in his guesses, although I'm not after a specific tone. The Splawn covers modded plexi to modded JCM800 territory. I guess what I'm looking for is something that is a bit darker, thicker sounding, but not sounding modern or 'recto'. NO DUMBLE CLONES, either.
The MJW sounds interesting, as does the Blankenship.
I'm looking for an amp that yes -- will play clean with some hair on it, can be cleaned up with a 5751 if need be, and will not fall apart when I hit it with a treble booster or fuzz.