I use the Diamondback redlines on my 1969 Corvette when it isn't being shown. From an appearance standpoint, they do differ from the original redline tires in that the redline itself is a raised (rather than recessed) ring of red rubber vulcanized to the side of the tire. They offer (used to anyway) a retread as well as a new tire that is manufactured for them under some "off brand" name that I don't recall at the moment. Obviously, from a functional point of view, they are superior to the bias ply tires that were OEM in just about every way. The ride quality is like night and day and if you plan to do a lot of driving with your car (but want to keep an original appearance) this is an option worth looking at.
As you mentioned, Coker also makes a redline radial, although I found that the sizes they offer are limited (nothing correctly sized for post-1967 Corvettes, I don't know about Camaros). I don't know if the redline on this tire is raised or recessed and I have no first hand experience driving on this tire.
There is a third manufacturer that I'm aware of using a Michelin tire as the basis for its redline, but I'm afraid that I'll have to track down the name if someone is interested in this one. The construction of this tire is identical to Diamondback's with a raised strip of red rubber vulcanized to the sidewall. I've driven a car with these tires and while there isn't a great difference in "feel," these are probably the tires I'll go with when my Diamondbacks need replaced (I like Michelin tires... What can I say).
It has been my experience for the most part, that the average enthusiast doesn't usually catch the difference in construction... The fact that it's a redline makes it a "correct" tire for the application. Those that do spot the difference in the redline and the fact that it's a radial, usually ask where they can get a set.
Good luck with your decision Daniel.