Could you be more specific about your budget? are you at 1K or 2K? ...can you make it to 5K?
Indeed, on the testing first try if it stays in tune when you go to the high notes, comparing with open strings (for instance: test the high E on 3rd string/9 fret with open E on 1 string. And then check the A on 3 string/2d fret with the A on 1 string/5 fret. If both the E and the A are in tune it´s a good signal things are ok).
Then you might also wish to play the notes one by one on the keyboard to check for homogeneity (typically for all guitars some note sound better than others...it´s kind of normal, nevertheless the more homogenity you have the better).
You can also look for buzzes (for instance: check the 4th string, playing notes all around a bit loud to detect if there are not some weakspot. my experience is that buzzes often affect this string, but perhaps this was just harzard for me).
You can also check the first fret, typically the F on first string to see if the note is a bit damped. This can also be a weak spot (which can however be corrected by a minor´s luthier intervention).
And then you try the high notes after the 12th fret on 1st string, to see how bright/long they last. Normally on a cedar you will have something with less sustain than on a spruce. Nothing wrong, just make sure you are fine with it.
And globally yes what really matters most, as wychmeus says, is that you like the guitar. Sure you cannot avoid discovering that the sound that first amazed you isn´t so amazing at the end, but I am not sure you can spot this type of things on first trial. Nevertheless, normally if you like the guitar, you like the guitar and you can trust your instinct.
I´ve checked on Dream guitars website, and they seem to have pretty interesting offers...although of course in the high end part. If you can afford it, I would definitely recommend taking the Bernabe Senior 1983, it´s a fair price for a rare guitar, likely to come up with a great sound. Then, with the Ramirez 1973 you cannot be wrong, but check the string heights (due to the long neck their soundboard showed a tendency to go up, hence strings height can create playability). If you can get it for 3000 dollars that would be better.
Hope this is useful. And please keep in mind I am no professional, just some feedback of my own experience of having acquired a few luthier´s guitar in the recent past.