converting 4 door buckets to hinged for 2 door

Yes I have. I done this to a bucket bench out of a 4door 71 valiant for my 75 dart. It is not hard. Just pop the lockring off of the figure 8bracket that holds the upper to the lower. Then replace it with the mechanism from your 2 door seats, bushing, lock-paw, bushing and d clip. The plastic trim piece even screw back correctly using the existing hole. The earlier seats are bolted but I have never seen a split bench being locked for a 4dr use