We know that the next version of the Mustang Shelby GT 500 is coming. We also know that it will have a supercharged version of the GT 350’s 5.2-liter V8. We also know that the supercharged V8 in the GT 500 won’t have the GT 350’s flat-plane crankshaft because it doesn’t take well to supercharging, for many reasons. 
Autoblog’s Joel Stocksdale‏ is at some Woodward event from which he tweeted the above picture. In a presumably unrelated article he wrote about the new 2018 Ford Mustang Cobra Jet. Now, I’m not the sharpest tool in this old Craftsman toolbox, but I’d bet some money that what you’re looking at above is basically the engine from the upcoming Shelby GT 500. 
It’s a supercharged V8 but slightly bigger in displacement than 5.2-liters. Ford says the Cobra Jet is conservatively good enough for mid-8 second passes, call it high 7s or low 8s. Now this a tubed and caged racer with huge slicks in the back. Simple math suggests that the power should be in the mid-to-high 800-ish horsepower level, 900-ish, perhaps?
So take that engine, reduce it back to 5.2-liters, put some emission-friendly tune on it, perhaps a slightly smaller blower than this 3-liter unit, add A/C, power steering, and all that crap, and you may have a street engine with 750-800 horsepower. Or somewhere in the Hellcat region, or just north of it. Horsepower wars, baby! What a time to be alive! 

http://hooniverse.info/2017/08/03/quick-spin-2017-ford-shelby-gt350r-mustang/