I assume you know that RPO N65 was not available for the 67 model year. Look here, and scroll down to line "N65" in the left column:http://www.camaros.org/pdf/options.pdf
Are you talking about a newer "doughnut" type spare, or the original type inflatable spare from back in that period? Are you trying to get something period correct or just a spare that takes up less space? You would need to give more info, like is the car stock or modified, does it have factory disc brakes, etc. The required backspacing is a factor. Here's a good place to learn the basics, click on the links in the first post:http://www.camaros.net/forums/showthread.php?t=33680
Aside from that, someone with more knowledge on the topic may chime in to help.