If you have a local shop that sells harps perhaps you could work out a deal where you could meet them at the shop and have someone local who is knowledgeable enough about the things you are concerned about to take a look.
It’s very possible you will need to get the harp “tuned up” even if it’s in good shape. I may be a bit spoiled – I live the in the Denver area and our local harp repair depot is run by David Kolacny who is not only very good at what he does, but also very patient and willing to go the extra mile to assist.
I wish you the best of fortune with this purchase – it looks like an incredible deal!