I doubt EVO-R taking the Z and putting it inside the 370z emblem is intellectual theft. It's not exactly a mind blowing concept.
I mean, you might as well contact Z1 about them taking your idea also, even if it's just the 350"z" and not the 370"z".
Motorsport! Chrome Big "Z" Logo Emblem, 03-09 350Z - The Z Store! Nissan-Datsun 240Z-260Z-280Z-280ZX-300ZX(Z31/Z32)-350Z-370Z Parts