I've read up on most of the computer letter combos and all that but i've never seen a "PK". This came out of a Tbird TC, and the part number is E5ZF-12A650-K1A.
Im honestly not sure if it will be better for the Merkur. If you are looking to do a lot of mods in the future, and itll plug in (i am also not sure if a repin is necessary) then I would use it.