I think the 6308 is pretty close to ideal for a street stock type spring on a restored Camaro.
It will lower the front about 1" though, from what I've heard.
I have a friend who picked up a couple of plastic spacers that fit under the spring that could be used to raise it up a bit if too low.
Check with your local alignment shop for them.
Check my web page for First Gen Camaro suspension info:
David's Motorsports page
First Gen Suspension Page
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Chev 350 Can-Am Vintage Racer