I know you want a bare minimum of 5.0l of displacement, but the Modular 4.6 can be built to put out the power you're looking for. Go for the 4.6. If you don't like that option and you have no insane brand loyalty, then go with a Vortec 5300.
i think when i get the money up (if i can get the money up lol) i will wind up goin with a 418 stroker with an EFI kit on it from Proformance Unlimited. Its gonna be expensive but the built great engines. have it modern on the outside and old school lookin under the hood with new school add ons. heres a pic and link with a video to the engine id love to have in my truck. The pic doesnt show the EFI on the engine but they have the kits for it. 418w Sroker, 408 Crate Engines, Ford Stroker Engines, Ford Performance Engine
I know that when i put a V8 in the truck i will also have to upgrade the rest of the drive train, brakes and suspension in order for it to work without breaking something when i get on the gas or attempt to stop.