One of the first stories I read on the Obama administration nixing imports of M1 Carbines and M1 Garands from South Korea was: Jung Sung-ki, "The U.S. government is opposing Korea’s bid to sell thousands of aging U.S. combat rifles to American gun collectors", Korea Times, 12 Aug 2010.
The ATF and the DOS came up with excuses for blocking imports, alternating between safety concerns about the old guns in storage for 50 years, claiming the M1 Carbine could fall into criminal hands, to raising questions whether the Koreans bought the guns from the US (theirs to sell) to whether the US loaned them. There were no consistent reasons why.
The Korean M1 Carbines and M1 Garands (potentially 700,000 returning to the US) have been a Obama Administration political football the past three years or so. I heard that 70,000 M1 Garands had been approved (none of the 600,000 plus M1 Carbines) then nada until Obama's announced executive order.
As to the shape of South Korean M1 Carbines, I have a M1 Carbine re-imported from South Korea by Blue Sky in the late 1980s. It was a 1943 IBM-made carbine, reparkerized with all the post-WWII arsenal rebuild updates: M2 style stock, adjustable sight, barrel band with bayonet lug, flipper safety, 3 nib magazine catch to secure 30 round magazines. The level of wear was what you would expect from a gun used from 1943 to early VietNam War era (early 1960s). Later problems showed up included a coil extractor spring crystalized and broke in two places (came out of bolt in three pieces when I removed the extractor). I also bought a replacement operating spring.