I have a Ford Motorsports "X-302" crate motor in my Cobra. They claimed it could make "up to" 340 hp in the sales materials. That would be "engine horsepower" not the rear wheel variety. On the chassis dyno when getting the EFI tuned, it actually made 290 hp at the rear wheels. This particular engine isn't sold anymore but, but a newer variation is (
https://performanceparts.ford.com/part/M-6007-X2302E ) that's still rated at 340 hp and it's specs should give you a decent idea for how Ford went about it for a crate engine.