The C102 alloy in my block is 99.95% pure copper (
http://www.fiskalloy.com/w-alloys-pa...opc102110.html). I actually do not know the alloy of my cold plate, but it is probably high copper since it was a cutoff from an EDM electrode.
Since87, if your copper is already annealed, why not test it, then pound and bend it, and test it again? I wouldn't know how to make a strip that small, and I don't have any work-hardened C102 left.