It is a constant fight to keep usable nylon strings on a classical guitar, so I can envision a scenario where you can’t evaluate the instrument correctly due to old strings. Add that to what you already know, and that is not to buy a guitar you have not yet played and I can see that you have a challenge.
I got extremely lucky 48 years ago when I walked into a guitar store in Pforzheim, Germany and bought my first guitar from a man who didn’t even speak my language. He was insistent that the guitar he was selling me, an Oscar Teller, was a great instrument and that has proven correct ever since.
Oscar’s Grandson Wolfgang still makes Classical Guitars in the same shop in Germany and has a website. You can post a message and consult him. He speaks very good English. He might can point you toward a US retailer where you can play some, or otherwise help you. He is a wonderful man with a passion for what he does.
https://www.teller-gitarren.de
Hope this helps.