i think you'd be better off with an attenuator..
all distortion pedals (not venturing into the botique market) (and note i said distortion, not overdrive) that i came across SUCK
they may sound good from the get go, but after a while while you get used to it, you hear a buzz in the heights which you cant get rid off, they're noisy (the bad way) and generic.
if you ask me, you should get an attenuator or power brake for the amp, then CRANK it with your overdrive in the front, which will give you all the benefits of the valves and still keep the volume down to levels, that wont leave you camping on the couch