Good question, and although I don't have an answer curious minds want to know...
I've daydreamed about putting a 5.0 in my 2007 STrac but see a few major obstacles areas in any type of engine swap nowadays.
After the mechanical part (alignment, transmission mount, driveshaft) I would think that the engine related electronics would be an issue (ECU, ABS, etc...). The donor parts could be brought over, but seeing how many sensors and software parameters there are this would be a major project in itself. A 4.6 should work but there's are a lot of variations even within the various Ford engine lines.
I used to do this type of swap back when carburetors still ruled the land but anything is possible, even when experts say it isn't.
Good luck!
Steve