I got a Fajen wood stock for my 1916 several years ago from Numrich. I had mine drilled and tapped for Redfield mounts. You also have to have a new bolt handle installed(rebent ones look like crap). You have to have the safety changed to a low scope model or change it to a Winchester model 70 style or put in a new trigger with a side safety. A new trigger will help tremendously.
Large Ring - Mauser's with a Large ring have a thread shank diameter of 1.10" With 12 threads per inch. Across the face of the receiver will measure 1 3/8 . You can also measure the trigger guard screw holes, From center hole to center of other hole should measure about 7 7/8 or 7.830.
Small Ring - Mausers with a Small ring have a thread shank diameter of .980" With 12 threads per inch. Across the face of the receiver will measure 1 1/4. You can also measure the trigger guard screw holes, From the center of the holes measure , it should measure about 7 5/8 or 7.625.
A Spanish 1916 is a small ring and the receivers are not heat treated. Factory .308's are the hottest thing they can stand and hold up for any length of time. They won't blow up or anything drastic but the receiver will eventually stretch making bolt operation difficult and finally impossible.
blasphemy that is what you are talking about. placing a plastic stock on a real gun is just that. That is like walking on some one grave. it is JUST darn wrong. wearing your hat at the table or wiping your nose on your sleeve they are all the same or it is like putting veggies in a margarita. WRONG......