Sounds interesting.. I'll have to look at that catalogue. The '78 catalog on this website has the 9000 and 7000 series, both made in Japan, and the 7000 series has the smooth ramp-shaped lugs. The other difference is the hardware. My set has clip rack tom mount, bass has telescoping spurs, and the bass cymbal L-arm mount is shaped differently than the later ones used by Yamaha. These hardware components share more similarity to the earlier drums pictured in the 1969 catalog, particularly the set model D-20. It certainly is possible the wood isn't birch, though, it is a tighter grain pattern on the 1st, 3rd and 5th plies but birch came in several hues, so it would be more informative to have a same-era Yamaha set as a point of comparison.

Still seeking more info, I looked up Camellia ply Yamaha and found this post on drummerworld:

http://www.drummerworld.com/forums/showthread.php?p=418550

They talk about a 70s Made in Taiwan series that is a Birch Camellia ply makeup. The drums pictured look like early Recording Customs, but again they're later than the drums I've pictured based on the mounting hardware which was indeed shared by the various series in the later 70s 7, 8, and 9000 series, later to be fitted with various lug types and called Recording Custom, Tour Custom and Stage series (and for a period of time, all 3 series made in Japan.)

Interestingly I was reading this month's Modern Drummer and it says that Questlove plays early 70s Yamahas, same size configuration but with that cool bowling ball oyster blue that I've seen on older yamaha sets, on the Jimmy Fallon show.