Pretty much what everyone stated above, look for a 'three piece' C logo.
Stay with the traditional lines, in the seventies the marketing department went nuts and started randomly introducing new lines of pipes pretty much willy nilly. A lot of these new lines were nice pipes, but they were coming at the end of the heyday and I tend to avoid them.
There are tons of good Traditions and London Prides out there for not much scratch, so if I were to want to sample the make that is where I would start (and London Pride pipes are actually quite high in the hierarchy). Get one with a stem that hasn't been chewed and you'll probably be OK.
The draw is tighter than what you would expect today from a artisan pipe, but pretty much in line with all pipes from the period and better than contemporary Kaywoodie or Dr. Grabow pipes.
I have had probably 300 Comoy's pipes pass through my hands, and keep about 15 in my rotation. What are you looking for in a pipe?
doc