I'm not sure about the "display" marking. Some bows were displayed just because, but others may have been marked "display" for more ominous reasons. I would do a very thorough inspection before stringing it up.
Also, I bought a '69 HC-300 Tamerlane without a mark on it. But after stringing it up and drawing it back, the finish on the limb backs cracked (cosmetic only) and in talking with the previous owner, he confirmed the bow had sat a very long time in a warm, dry location. The bow shoots fine, I'm just relaying this so you won't be surprised or disappointed if it happens.
S/N 7XXXXX does not guarantee yours is a '67. I sent you a pm with some info I wrote up regarding the Tamerlanes. Enjoy!
Here is a pic of my '64 Tamerlane...showing the SN beginning with a 7