Hi Toby,
I must admit I always read the "gold borders" as meaning gold edges, however now I see that is not what was being described. I have the girl standing at the beach, but she is in a No. 504 box. Is it possible the numbers correspond to the different backs?
Actually, gold borders could be just that - gold borders. Instead of a uniform band of white surrounding the back art, it would be printed into the bleed area with gold ink. It was meant to look nearly as nice as a gilded deck but at a somewhat lower cost. I can't say this for certain, but my bet would be that you're looking at a different model number on your box because it's for a different deck in the manufacturer's catalog - gold borders versus gold edges (a.k.a. gilding).
It's also not impossible that someone took that box and slipped a gilded deck into it - it happens a lot with older decks. It's easy to understand, as well, that someone might confuse gold borders and gold edges, thus slipping a gilded deck into a box for gold-bordered cards.
When decks are this old, it's pretty common to find that the box fell apart long ago and no decent fragment of it remained with the cards. I was always astounded at how the cards themselves could outlast the thing meant to protect them from rough handling, wear, light and dust. But if someone wanted to protect a deck and the original wrapper or box was destroyed or lost, they'll grab the next best thing - the box from another deck.