I have a pair of Emblem that says “Powered By Ford”, on my Cobra. Some say the 427 is the body and some say it's the motor. If you like them, use them. It's your car. Shelby built 348 Cobras with 427's or 428's, most had the 428. I think all had the 427 badges. I see a lot of people pull up beside me and read the badges. I see their lips say "Ford." If someone ask me if I have a big block or 427, I ask them what does it sound like. They always say big block/427. I have a fuel injected small block. I am alway nice, but I'm driving the Cobra and they in "what ever." Most people don't know and don't really care.
Enjoy your Cobra the way you want to.
Dwight
I'm going for popcorn now and I'll be right back