Lots of 1893 type actions have been rebarrelled for the 7.62 NATO. They seem to hold up all right for at least a limited amount of firing. (Range sessions, hunting. I don't know about 10k endurance tests!)
Actually the rifle is about as strong as the '98 locking wise. The lack of a safety lug bothers a lot of people, but for a safety lug to be needed, both front lugs have to break or shear. This is unlikely in the extreme with any reasonable load.
They also don't handle gas escape from a blown head as well as the '98 does.
I have fired those Spanish conversions and never felt in danger. I would stick to NATO spec military or moderate handloads; some commercial ammo is pretty hot for the old guns. A headspace check would be a good idea.
Incidentally, they were intended for the Spanish standard 7.62 NATO loading, not the light CETME loads.