Yes, there was an RS/SS model of the first-gen. It was an appearance trim/engine package combination.
The Z28 had a twitchy, high-revving 302 motor which gave the Camaro a lower weight and a beast of a track car. In 1/4 drags, if the "big iron" higher-HP blocks could hook up, not bog down or go up in wheelspin, it ~might~ with a good driver, drive around the Z/28 in a 1/4 mile. This probably happened less often than you might think.
The SS was a bigger displacement, heavier car with much more HP, and better performance numbers.
But, as an overall car, the Z/28, IMO, was regarded as the more "fun" car over the SS.
In fact, the Z28's still command a higher premium in auction over the SS's, from what I have seen.
Only the COPO cars command a higher premium. And it can be argued those weren't truly "production" cars since they were hush-hush "you had to know the code" cars that were limited to very few built units.
The SS may have been more popular, but the Z28 was more revered, as far as I know.
Therefore, disregarding pure HP and other specs, in the grand scheme of things, the Z/28 was "The" Camaro to have.
It was a nervous, twitchy, fun, and dangerous car to drive. It screamed, swayed, barked, and groaned.
The SS, with its bigger bloated iron, was the "hold it in a straight line and wait for the cubes to walk in the end" while hoping your rear tires didnt boil, and hoping it didn't bog while waiting a year for revving through the gears.
So, despite horsepower and displacement, the Z28 should be the "top dog."
And, as others have said - it's a purist Camaro thing. There never was any other Z28 model car, other than the Camaro.
To me, in modern equivalents, the FIRST GEN Z28 Camaro = Z06 Corvette. The SS Camaro = ZR1 Corvette, even though this doesn't jibe with the whole "top dog" theme, nor power estimates.
As what happened in the past, I believe the Z06 Corvette will be better-regarded as "the" Corvette to have in the future, while the ZR1 is a "show-off" car that doesn't really hold as well in the future.
No wonder people are confused!?!?
Some "facts:"
"Available 1969 Chevrolet Camaro Models:
Camaro Base Coupe
Camaro Base Convertible
Camaro RS Rally Sport Coupe
Camaro RS Rally Sport Convertible
Camaro Z28 Coupe
Camaro Z28 RS Rally Sport Coupe
Camaro Indy 500 Pace Car Replica Coupe [X-10]
CAMARO Indy 500 Pace Car Replica Convertible [X-11]
Camaro SS Super Sport Coupe
Camaro SS Super Sport Convertible
Camaro SS RS Super Sport Rally Sport Coupe
Camaro SS RS Super Sport Rally Sport Convertible "
http://www.firstgencamaro.com/1969.html