The 4.6 is a squeeze but if you can fab motor mounts it will be doable. It will be easier with the cab off.
If you have a coil spring truck the motor plate design most used is from BrainB over on RPS. If you have a 4wd explorer 5.0 mounts are bolt in.
Headers will be an issue if you choose that route, TM are expensive and produce meager gains.