I had the good fortune to handle one a few years back, it appeared quite well made, the magazine adapter was VERY nicely executed in machining, but did not explore any changes needed to the release button. There were a few customizations that made it less than perfect in terms of commercial attractiveness: The magazine adapter was inserted from the top and rested on the lower with a lip. This required material from the upper to be milled away to make room for this lip, which meant a pretty much dedicated system. Also, due to the slightly smaller rim size, it was my understanding that Oly was making custom bolts (or modifying .223 versions to fill the extra space...). Either way, a time and money intensive ordeal.
A certain foreign government used the M1 Carbine extensively, along with some of the "extension" services (armed citizenry). Several projects were undertaken to give the M1C a "face lift" or otherwise make it more suitable for modern applications. Why? I dunno, seems that with a nice MRD and a folding stock, these are some sublime pack/truck carbines...