Love the brownies! There is a really clean 'center volume' Concert (very early, probably from 1960 but I didn't check the stamp on the tube chart, 5 preamp tubes, bass/treble/volume knob order instead of volume/treble/bass) sitting in a shop in Scottsdale that I have been drooling over, but I am actually starting to purge gear since I got my AxeFX3, as most of my tube gear is too loud to be practical for home use....
BTW, the Super and Concert use 2x10 and 4x10 speakers. This early in the '60s, they would still be AlNiCo Jensens, likely P10R. I use a Super Reverb cab with the 6G12, and a Vibroverb 2x10 with the 6G4, generally. Great sounding amps! I still want to kick myself for not buying the 6G4 back in 1991/1992 for $400. I ended up with a '72 Super Reverb instead.