Jim,
the MGB doesn't cut it anymore?
I don't think you can really make a competitive car in GT1 with a "Cobra" The wheelbase and aero are against you. If the Daytona coupe was homologated you might have a chance but SCCA does not recognize the coupe (it was an FIA loophole that allowed it)
But if you just want to go fast and make noise, go for it!