I would ask what makes the replacement a necessary thing?? and ask why you would not rebuild the carter you have? The MC 2100 is more than likely a better carb but it will not be a "plug and play" you have issues with the fuel lines, linkage and air cleaner to deal with and if you look through the archives you will find more than a few guys cursing the day they paid some guy on E bay for this crappy carb.
For this reason i think doing the carb in stages is is a good thing and a great learning experience.
rebuild the carter make it run well and you have something to compare it to.
Go to the grave yard and pick up an MC2100 and everything you can pull related to it and do the kit on it, find the adapter and design the linkage, work the air cleaner problem out and then tell us how much of an improvement you actually made.
when all this is done you may very well have made the Jeep better but you certainly are closer to being a "Jeep guy".
There are plenty of places to spend money on your Jeep so save the money for something you really need to buy.
$250 for a carb, $20 rebuild kit, $40 junk yard carb. do the math.
If working on your jeep is not a fun thing, you may want to rethink your vehicle choice.
For me, I think the obvious upgrade is fuel injection. No matter what you do, a carb is ancient technology. Drag your Jeep into the new millennium.