As for old Spanish (early 1900s) converted from 7mm to NATO .308, some middle-aged gun show buddies who are very familiar with Mausers are really skeptical about the strength of the Spanish steel from 1916 or so.
Chilean 1895 Mausers were made by Loewe, owner of the original Mauser Werke, in Germany (home to Krupp steel). Metallurgy on German mausers is far from suspect.
1895 Mausers are stronger than 1893 Mausers, having better heat treating than the average Spanish Mauser, and have the added benefit of the Mauser Safety, a lug behind the bolt handle cutout that would use the bolt handle as a safety lug in the event of a catastrophic failure.
That said, I would trust an 1895 Mauser for occasional shooting with 7.62X51mm NATO, but a steady diet of high-pressure 308 loads will start to peen the action, causing growing headspace and making unlocking the bolt difficult.