Technically you are correct. It's not the exact same engine, but here is what autoblog says about it in their interview with the head SVT engineer:
"We recently had a chance to sit down with GT500 chief nameplate engineer Jamal Hameedi in his office at SVT's headquarters to learn more about what's new for 2011. Switching to an aluminum block was a bit more complicated than simply digging out the casting molds that were used for the GT. The engine in that 200+ mph supercar used a dry sump lubrication system and featured iron cylinder liners. The new GT500 engine is derived from the structural design of the older block but retains the wet sump system used in other Mustangs."
Seems that the GT500 has a better engine? Not that I care. I still want the Mclaren with my fictional money.
