Sounds like you have a L34 or L35 SS 396
an early one would have the narrow rear spoiler, as you have already verified.
1969 Camaros had Z28 emblems added to non Z28 cars starting in 1969, so just because it was on there for 20 years really means little.
You never mentioned the build date, but based on the narrow rear spoiler I would guess an early build, and that would also include the "straight" head rests and the two piece kick panels.
Lots of great experts are over here:
http://www.camaros.net/forums/