It is definitely possible on a comfort bike, but probably not the most comfortable or fastest way to do it. I would suggest working with a fit professional to figure out a fit that can be comfortable to you without stressing your old injuries. You may be able to get a relaxed geometry road bike like a Specialized Roubaix or a Trek Domane that would allow you to be in a more aerodynamic position without aggravating your injuries. Or you may find that your current comfort bike is perfect for what you need. Either way, I have seen people do the MS150 on mountain bikes, on unicycles, on single speed road bikes, etc. I have also seen a guy riding a full suspension mountain bike hang with the 18-20 mph group on the NWCC Saturday morning ride for 24 miles. That group probably averaged 22mph for the stretch and he managed to hang with them.

So it really isn't about the bike. I would 2nd the recommendation to just start stretching out some of your rides and see how far you can comfortably go. I always tell people that if you can get the fitness capability to ride 20-30 miles, you can do the MS150. Beyond that first 20-30 miles, you aren't really dealing with anything new from a fitness standpoint...rather you are just getting your back, butt, neck, and hands used to being on the bike that long. If you think of it as riding 10 miles 8-9 times instead of riding 80-90 miles, it gets easier. Just don't plan to stay at the rest stops too long as that will kill your overall average speed and make the ride take a lot longer.