A bored and stroked 351 for 427 cubes is going to be the simplest way to get your horsepower desired. Personally I have a 347 with 4x2 Webers and love it, horespower wise around 400+. Runs fine on 93 octane fuel. No longer available but this is my Ford crate engine installed by PO 347 - 450 Horsepower M-6007-Z347 | Ford Racing | Crate Motors | Crate Engines | FordPowerShop.com IMO thats plenty of HP for a car this size/weight. I also think either way go with aluminum heads to reduce front end weight also. I've never driven a BB Cobra but can't imagine it handles great with all that front end weight. I would also recommend a rear IRS over the 8.8" rear. My car has a 8.8" with 4 link but I am converting it to a 3 link for auto crossing this summer.