As a fellow Cobra owner who
also owns a turbo "rice burner" (Impreza STi- say what you will, then meet me on the AutoX course!
), there's a lot to consider to the equation...
First off, while a smaller displacement engine is capable of big power, it has to work much harder to do it. Harder work= more stress.
While it is true our cars are lightweight- it's a relative thing; mebbe it's not needed in a 1300 lb Lotus or an F1 car, but torque is VERY important in a Cobra replica, IMHO.
A car w/ plenty of torque will be
much more streetable than an equivalent car w/ the same hp, but lower lbs/ft.
Just my opinion- your mileage may vary,
Russ R