NHRA rating for the Cobra model is 252 for stock and 235 for super stock. Doesn't matter if it is the R or not, the model only affects the shipping weight since both versions have the exact same engine. Stick only. Both versions are natural "I" classification.
You will want to ditch the OEM computer and put in an approved aftermarket EFI system like FAST similar. There is a list of approved EFI boxes at
http://www.nhra.com/userfiles/file/N...edProducts.pdf on page 96.
Good luck, bring lots of money and patience.