Any clone or reissue JCM800 is what you want... PLUS a pedal. Why complicate things? When you want that legendary base crunch, that is the circuit you want. The others mentioned are all killer amps but look under the hood and there are enough changes in the circuit for it NOT to be an 800. (Besides the 800 KK,) The ceriatone molecular sounds great to my ear and is the one I would get but it isn't 800 and I don't hear that raw dry 800 crunch from it. I hear more turned down saturation. Nothing wrong with that, BUT more often than not people looking for what you are looking for circle back to the original. Just get an 800 clone from Ceriatone or a builder. It is like people searching for the "plexi" tone, getting an actual Plexi NMV style amp is what allows them to see God, not a MV amp pretending to be a big boy.
OR, if Cameron ever releases his diode clipping Hotmod, then you can get that tight gain all day long from an 800.