If you can still find it, look for the One Lap of America LS. Ford engineers (who had access to all the stock programming) shoved a 4.6L engine into an '03 LS. They never could get the electronics to work right. They also had a cooling issue they, AFAIR, couldn't really cure. And the guy that put the LS engine in also had to have custom, stand-alone gauges (speedo, tach, fuel level and water temp) as the factory set wouldn't work (electrically). That car has also had more owners than NObama has lies!
The LS has more in common with a Jaguar than any Ford. Do yourself a favor. Ditch this idea and spend the money on a Jaguar S-Type R. Unless you're just looking for a stylish drag car......