While the gun appears old, guns like that were made in Spain well into the post WWII era and updated versions have been imported quite recently.
They were/are the product of small groups of gun and parts makers, mostly in the Basque region. In the traditions of cottage industry, the work was mainly by hand, done at home. One guy made hammers, one guy sears, one guy stocks, etc. A small shop with some machinery made the receiver. Barrels and stock blanks were usually bought from larger companies. Everything was hand assembled by another small "factory"; specifications and quality control were unknown terms. Any markings indicating a maker are also absent, though guns made in the 1930's and later will show Spanish proof marks.
The plus side is that they are interesting and literally unique, as no two seem to be exactly the same. The down side is that you will learn to dance a Flamenco before you will ever obtain parts or find an American gunsmith who will agree to work on one of those guns.
Even more of a downer is that the parts are rarely made of good steel or properly hardened. They are generally thinly case hardened and tend to wear through the hardening with use. Also, since the hardening is only on the surface, any impact (like dropping the gun on a cocked hammer) will cause the soft parts to shear.
Sorry I couldn't be of more help. This is in reply to your personal message also.