Something to think about maybe:
Corvette ZR-1 Ring time: 7:26.4 with 638 bhp...
The official curb weight of the 2009 ZR1 was released to be 3,352 lb (1,520 kg).
Nissan GTR Ring Time: 7:26.70 with 530bhp (and two cyls less)
Curb weight1,740 kg (3,800 lb)
If a Jap can keep up with a ZR1, why wouldn't a Z28 be able to beat a Z06 (which is supposed to be a slower car than the ZR1)?