Whatever Ford do, GM will combat - so if there's a GT500 mustang, I expect we'll see something similar from the factory.
We're a year from showrooms now - so the engine, whatever it is, must exist by now. The LS3 seems a good bet as the Corvette will have had that exclusively for some time - and the GTO got the LS2 so I can't see why the Camaro wouldn't. Something blown will have to come later on...
2005 Vauxhall Monaro VXR. Sport pac - Road Response Pac - Ripshifter
2005 Vauxhall Astra 1.6 Sport (ug)
2001 Honda CBR 600 F