I believe the 04+ LTD's came with larger brakes and only the 03 LTD were the same as the 03 SR5.

With that in mind, swapping rotors and calipers are pretty easy for an average wrencher. Just purchase the Toyota Service Manual (TSM) from ebay (I've seen em as low as 100 bucks shipped for vol 1 and 2) and do the swap. Check out Toyota junk yards for parts and go from there.

It does take some labor but any qualified person can do this easily. Since you're planning to do the suspension upgrade, you might try to do the disc/caliper swap at the sametime. I know Jason can do this with no problems so long as the parts are available so look into that option.

Good luck