[sr71]

That would be a very nice choice. However, since you're putting in a Cobra there is nothing that's generates a smile faster (for you and the people that you show it to) than stack injection (or Webers). For this reason you might want to take a look at the 353 IR or the 402 IR. The 427 small block (any 427 small block) is in my opinion a little too close to exploding for my liking. If you decide to go bigger I see that Roush is now offering a 588R.

From a handling perspective the 342 or 353 are the lightest (302 block) and will give your car a very nice balance. The 402 (351 block) will step the weight up a bit in the front and the 588 will really make the nose heavy.

For my next Cobra..... I would probably go with the 402 IR.