As mentioned above, the Tourmaster 2x12 is a perfect match for the MOD50. Tolex and grill match perfectly, and the Celestion Elite 80s (basically CL80s) are really well balanced to maximise usability when using modules with different tonality (ie. Fender / Marshall).
The USA made 1x12 is a tiny bit smaller than the Chinese made Tourmaster 2x12, but is oversized and still quite large and heavy. It looks like it could easily fit a couple of 12" speakers if placed diagonally, and as mentioned above is big enough to be a 4x10" cab.
Another really good thing about the Tourmaster 2x12 is the removable back segment that lets you convert it between an open and closed back. That cab really does do it all and sounds fantastic in any configuration. And the removable wheels make it much easier to move around. Like any birch ply 2x12, it is very heavy.