Robert,
These Spanish army surplus rifles are Model 1916 Mausers, which is a Spanish arsenal (Oviedo) built variant of the M1893 Mauser.
The general opinion among gunsmiths is that these early Mausers are NOT safe when chambered in .308 Winchester/7.62x51 NATO. The rifles are chambered for a reduced power Spanish Army cartridge (7.62x51 CETME) dimensionally identical to the 7.62x51 NATO. You are taking a big risk to fire .308 Winchester in them.
The many reasons include: old design, marginal quality control, poor gas handling in case of ruptured primers/cases, lack of a safety lug, and general condition of mis-matched parts in surplus arms.
You would do well to save your money and buy a better rifle specifically designed for the .308 Winchester.
HTH
John