The GBS8200 board could be trimmed from the bottom up to the three RGB pots with minimal rewiring required (RGB+sync signals, buttons, etc.) You could also trim off the whole right side where the original microcontroller is, but you'd need to rewire some voltages and other stuff if you did that.
I'll make a thread for my αSNES project when it's ready, but the redesigned SNES is about 70x70mm.