Engine Choice Roush 342RE vs 427sr/tw

[TimeForACobra]

I'm considering purchasing a cobra... 2 different manufacturers and 2 different engines. Can I get some of your thoughts about which engine would suite me the best? The 2 engines are the Roush 342RE (fuel injected, 450hp, 420 ft.-lbs.) and the Roush 427 SR w/ TW (carburated, 515hp, 535 ft.-lbs.). I imagine either engine should be plenty in a Cobra. I plan to use the car as a cruiser, just enjoy the car. I also plan on getting back into autocrossing (I will buy an extra set of wheels with sticky tires and a trailer). And lastly, I hope to try an occasional track day, maybe once or twice a year. Any opinions on which engine will suite me best? Both cars have a limited slip rear. The 342 has a 3.72 rear, the 427 has a 3.64 rear. Both have Tremec TKO 600 transmissions. The 342 has the transmission with the 2.87/.64 Road Race Gears. Not sure of the exact transmission gearing of the 427.

Advice? Thoughts? Discussion?

As always, I appreciate everyone's input.