Joined: Nov 2016
Arch, while this swap is possible, it requires a lot of dedication, hard work, and money.
To fit the engine in an early 'Stang, the entire front end of the car must be cut up to remove the shock towers. Then, the front suspension must be replaced with a Mustang II type front suspension (which doesn't require shock towers). That makes the front end very floppy and weak, which requires a lot of additional frame bracing to support. The new engine produces enough power to bend the rest of your frame, so you'll need subframe braces too. Your rear end will need to be upgraded to a 9", and you'll probably want some traction aids to prevent wheelhop. The driveshaft and suspension mounts have to be swapped out too, and there's a lot of wiring involved.
In the end, this swap usually costs a minimum of about 10k, if you do most of the work yourself, and already own the engine.
IMHO, the end result is a nice fast car, but you can achieve superior results with a pushrod Windsor. My advice? Sell the 5.4 for a small fortune, and build a wicked aluminum-block 347 or 427 Windsor. It'll fit better, you can keep the original frame bracing, enjoy superior front end geometry and ride quality, lighter overall weight, and even more power than your supercharged engine with better reliability.
I smile a lot. It makes people wonder what I'm up to...