I don't think the 5.5 DOHC will make 600 lb*ft torque, probably more like 470-475. I've been rooting for 650 hp, though. If they can get 410 lb*ft at 8000 rpm, that would be 625, so it would be in the ballpark. If they make less than 650, people will think they're going backwards from the C7 Z06.
I have been watching IMSA races all year, where they are running the C8R with the 5.5 DOHC flat crank engine. I hate it. It emits an annoying buzz for an exhaust note. I think GM is trying to emulate Ferrari with the flat crank engine. That's just wrong. CORVETTES SHOULD THUNDER, NOT BUZZ. Put a crossplane crank in that thing.
If the aftermarket tuners can develop a supercharged small block package with 650 hp, they could sell a lot of them. GM has left a hole in their engine lineup.
What do you think of the recently-discontinued Mustang Shelby GT350 Voodoo flat plane V8?