I bought a 2000 GT with a blown Windsor motor. Installed a 2003 Romeo from a Grand Marquis. That was 3 years and 50k miles ago. So count me as someone that has done the swap.
Very do'able. Mostly straight forward. Works best if you can place both motors side by side and transfer parts from one to the other.
2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.