M14 was issued to US Army in 1958, I think, and to Marines in 1962.
The real stock will not fit ASC M14 because of the motor in "grip". The AS stock is 0,5cm wider then the real one, if you dig out a space for motor in real stock it would be very thin and in case you hit the ground hard it will break.
There would be possibility to let someone to make wider wood stock. It would be great.
Semper Fi