Yes and no/yes if you know what you are doing. I believe they have procedures on the internet that can help do you do this. The exterior converter sounds much more safe and helpful, plus you keep the machine unmodified.
I have a MC50 and an MC250. I love them both. I like the Mc50 because it is light and easy to move (18lbs). It doesn't have as large of a foot print and can push a 2x12 fine as long as you have a good preamp like an SMS or Fender. I especially like using a 1x12, plenty of volume, I use it for small bar gigs all the time and still have headroom. If your band plays really loud, then you may want the 250 or 2100. The MC50 is a rare find lately, but worth the pickup if you find it! Even if you plan on buying something more powerful like a 250 or 2100 in the future. Most audiophiles want stereo so some won't compete for it on ebay since its mono.
I bought the MC250 (about 30 lbs) to be able to push more volume, and it does, plus have a stereo situation if I need. This is a more versatile option for you and it can be bridged into mono 100watts. never had to, but I can. I can use one half of it and save the other as a back up amp. I can also hook up each speaker to separate sides of the amp to control volume on certain speakers.
I have used a lot of amps in my time and love the MC's more than any other amp I have used, in term of tone. They are not fun to transport (no handles), they don't rack up easy and neatly, it doesn't look pretty and sparkly with lights and such. Only one knob for gain, that's it. Unlike a Rocktron, Mosvalve or other modern amp you loose some of the tonal shaping tools. I have enough shaping I can do otherwise in the preamp, so I would never go back to a modern amp for that reason. They sound fat and organic kinda like a tube amp or at least not what you would think an SS amp would sound like, and it has a linear gain without that tube compression at high levels. Plus you don't have to buy tubes anymore. There is a reason why a lot of Jerry guys use them. Working on it is easy too, i guess if you know how too. Its easy to access under the hood at least.
Hope this helps!! JB