Oh no, not gunna get into the Z28 vs SS battle....
In a nut shell, SS was a hood scoop, wheels and exhaust over Z28 for the 4th gens. Untill then Z28 was king.
The new SC 6.2's are just the begining. Remember that GM could easily make 500hp out of a direct injected 6.2, and they already have. The test mule for such engine exists as a 08 Escalade and it makes "well north of 450hp" and that is with the truck L92. The LS3, its higher performance brother, makes 40 more hp over the L92, so a 500 hp 6.2 could be easily done, and that would make more power then MB 6.2
The SC motors will be great, and the LS9 is said to be DI, hence the massive power over the other SC 6.2's. We could very easily see a 650 stock ZR1 Vette, and just a simple pully and tune away from 700+.
No, it wont come under 70k, not with what they have planned.