Quoted from a source whom is usually correct...
Major turmoil over at the Ford camp is causing major changes as I'm sure you can imagine.
As of now the 5.8L Boss engines are slated for Mustangs but not until
2010 earliest maybe 2011. 6.2s are now relegated to truck only duty.The new push for the Boss, and most at Ford don't even know about it, is back to a 5.4 4v using GT/GT500 heads and a new intake. Obviously this would be the most cost effective route for a Special Edition that's supposed to come to market in the near future. Evidently they've made 380hp (not sure if its rear wheel or flywheel) with off the shelf cams and this motor.
There is still zero chance of a big bore modular 5.0 ending up in the Boss Special Edition.
Sorry for all the changing info, but it's the price you pay when you want the most current info vs. waiting.
Davïd Greenville, NC