You'd be looking at 340 - 360kw and around 11l/100km.
Traction control and ESP work quite will on the SS and they have become a much better car than Ford.
Holden will continue to support the cars for over 10 years after manufacture so will Ford so no worries about parts really.
I just serviced my 5.7 and the belts were $58 for both trade price inc GST.
The ford belt is twice that for one!
Plus if you want to DIY the cars the parts are available from Summit racing for peanuts!