Bruce, in addition to the US Federal import regulations, might also want to inquire with the DMV in the state the Cobra would be registered in. The individual states have their own inspection and registration laws, which in a number of cases, is not consistent.
A number of states have implemented the SEMA approach, but there could still be individual differences.
As an example, all kit/replica cars in CT are registered with the make as a Composite and the year first registered in CT is the model year. Aa of June, 2007, all CT Composites are exempt from emissions testing. The CT guidelines are mentioned in the following document:
http://www.ct.gov/dmv/LIB/dmv/20/29/R-157.pdf