Black Wolf, I personally would not worry too much, especially if the receiver does not have the selector cut out, my old M1a does, with the matching M14 stock, but the trigger group won't support the selector if I had one. Trw makes excellent parts for the M1a, that is a plus.As I have gotten older, the match M1a's with the heavier barrel, don't hold as much charisma, my rack grade shoots great and is a lot lighter, although I did do the national match sight upgrade.
Hope you and your family are doing well, call me when you can.