I've tried to read most of the stickied thread, but I would like some clarity.
Thinking of doing the swap, I think it would be neat...
Anyways:
1) What years would be suitable, Its an 03 GT
2) Does all the wiring hook up?
3) What about the 3 valve from the 04+ Trucks
4) If I plan to supercharge it, what to look out for?
5) Or the best N/A options, cam, port and polish etc
6) What parts are interchangeable between the engines

I'm still just wondering if I should do it, it looks like it will be hard to find the engine up here for a reasonable price. I like the thought of telling people I have a 5.4L, and such. And there's "no replacement for displacement"

 

In order:

1. You'll need a block from a pre-04 (01-03 is ideal) for your 03.
2. You use your stock wiring. it'll all hook up in the same places if you stay 2v.
3. 3v is worth a lot more power if you put better cams in it. It's a good bit more complex but not super hard and hood selection may be an issue.
4. Use good forged H-beam rods and forged pistons. H-series rod and main bearings help too. some windsor 2v's like to spit out plugs at high boost. You can heli-coil the plug holes to treat that problem or make sure you use heads with a full 8 threads engaged. Watch out for extremely high tq at low engine speeds. Traction becomes iffy.
5. 4v heads=high lift cams, short runner intake, forged bottom end... could be beefy. 2v heads= vt stage 2 or comp xe270 to xe278 cams, mid length runner, full race head porting, HPS or P51 intake and adapter plates or custom intake.
anything that's not inside the block generally except the pistons and bearings are the same.

Use ARP fasteners too. Basically you want a built block for any performance application where you're going to beat on it. Stock rods are kinda weak sauce.

If you've got a mind to spend 3-6K and have NA power that'll last it's totally worth it. Blowers on 4.6's are fun too but eventually you're building a motor anyway.

 

Wooooooooooow, I am so pumped so really I just need the block, and buy forged internals, and an intake?
Now I am looking for an engine for cheap.....