Montaya's were made by the Hyosung Corp. in South Korea, during the 70's. That doesn't mean it's a good guitar ... or a bad one. A lot of very good acoustics and electrics are made in South Korea, and are known for their workmanship.
The main thing to watch for with an older acoustic is for signs of moisture / dryness damage. Have a look down the length of the guitar, looking at it from the bottom straight up the neck. Looks for signs of warpage in the neck. There should be a very slight concave curvature in the neck / fretboard (called "relief"). It should be enough so that there isn't any fret buzz when strummed open or when fretting. But there shouldn't be so much relief, that the action (string height from fretboard) is so great that it's hard to play.
Also notice whether the top of the guitar is concave / convex. Look for a hump on top of the soundboard, between where the neck attaches and the sound hole. A hump here usually means the guitar has been dried out too much (improper storage) which is very hard to recover from once the wood has been re-shaped. Also look for lifting around the bridge. Here's a great article with more detail about inspecting a used guitar:
https://www.sagemusic.co/inspecting-an- … condition/
If the guitar is straight in these areas, and also plays / sounds good, you've probably got a good deal in your hands.
Let us know how you made out ... all the best!