I have a set of 4 AFS Cobra center caps that came with my new Mach 1 replica wheels. I think they would look great on somebodies Cobra, but I'm not into mix and match. They are brand new and were on the wheels when I got them. I took them off before getting my wheels/tires installed.
Info from the AFS Wheels website about the center caps.
ITEM DESCRIPTION: This is for a complete set of four center caps - AFS Cobra 2.56 inch (1 unit equals four caps)
WHAT THEY WILL FIT: These center caps will fit in the Ford Mustang Cobra style wheels. They will also fit in the OEM Ford 2003 Cobra wheels, 94-04 Bullitt wheels, Mach 1 wheels, Y2K wheels, SVT, GT, AFS and many other aftermarket wheels.
SIZE AND SPECIFICATIONS: This center cap measures 2.56 inches in diameter (2 and 9/16 inches)
Here is the center caps link for AFS's website. Cobra 2.56" Center Caps 4 Ford Mustang Bullitt Mach1 Wheels Set
$50 shipped USA (would need to check cost for Alaska and Hawaii)