I'd go the 351W route. More reliability, unless you go nuts on the build, more streetable, and you can ring some great hp and torque out of them. Plus the parts are less expensive and there is less weight to deal with. I overbuilt the 429 in my first Cobra(couldn't afford a 427so)it was not very street friendly and handling was a B!TCH!:( And way more expensive to build than if I'd gone the 351 stroker route.
Speed= hp-weight:)