Very little trouble. But for not much more $$ you could go the PI route from a 2001+ Town Car, Crown Vic, or Grand Marquis. Check car-part.com for sample motor prices in your area.
Just put both motors on an engine stand. Make the donor motor look like the original. Oil pan, motor mounts, exhaust manifold, intake, ignition, wiring harness, fuel rails, fuel injectors, front acc, flywheel/flexplate. Doesn't get much more straight forward.