Finding a good first gen RS/SS big block 4 speed with numbers matching is
like finding a virgin hooker--
extremely improbable. I study Camaro prices obsessively, and I can tell you
that a numbers matching
Camaro RS/SS 396 in ANY condition will cost you a premium price. You can pay
over $25K for one
that needs complete restoration if it is all numbers matching. So, it
depends on how deep
your pockets are, and how long your intend to keep the car. Another factor
is what you
plan to do with it-- it can be almost too risky to use a highly optioned car
for a daily driver, kind
of takes the fun out of cruising if you are always worried about someone
scratching your
car at the supermarket.  I owned a '67 Camaro RS/SS a few years back but
sold it and purchased a '68 Camaro sport coupe
to restore, and it was a good move. I didn't want to modify anything because
it might hurt the value of the car.
This '68 is almost completely restored, I've had a hell of a lot of
fun with it during the past couple years, now I'm thinking about selling it
and doing another Camaro restoration.

The stakes are so high nowadays with the RS SS or Z/28 Camaros that you
really have to stick to stock and/or original parts.
But with a 'plain jane' Camaro you can build it to your ideal vision of a
Camaro.
Originality is a plus, but your car won't go down in value if you decide to
go with
a custom paint job, or mag wheels, or a high-performance engine, or a 5 or 6
speed
transmission, etc. There are still some sport coupes around in relatively
good shape
for under 10K...

BTW I once owned a '64 Mercury Comet convertible, sure wish I had kept it
and restored it!

Terry M.