It's a mixmaster, near as I can tell. Unless the inked on numbers are assembly numbers rather than serial #s. Regardless, I don't think that stock fit ANYTHING properly.
Oh, well, it's money well spent just for the educational value alone. I still would like to fine one in "pretty" condition, but the only Spanish rifles I ever see are ratty carbines or scary recalibered things. Maybe an FR8 would be fun, but otherwise I'm only interested in the original '93 model.
I don't think this rifle had been apart beyond removal of the bolt for 50-60 years, judging by the crust that had built up.