I can suggest two alternatives:
1. Edelbrock used to make (maybe they still do) a classic, finned valve cover for SB Chevys that had the 'Edelbrock' script in the middle. The hard part is finding some that have provisions for breather caps/PCV valves, as they were originally designed for the early SBC that had a front breather tube jutting out from the intake.
2. 1969-1973 Corvette/Camaro "LT-1" valve covers. Classic finned aluminum design with a nice cross-flags applique to one side. Has provisions for breathers/PCV. You could have a local graphics company do you up some vinyl "Cobra" logo and glue it over the same location. Or cut yourself a thin piece of aluminum/tin, take a Cobra hood/trunk emblem, grind off the mounting tangs, and epoxy to the tin. Then epoxy the tin to the cover. Done.
Just be careful of the funny looks you get at the next car show.
-Dean