I am keeping a open mind on the 5 litre eater, 5 Litre VP, VR, VS, VT aren't that fast. However a V6 VN is the fastest V6 commodore yet, at 1320kg the power to weight is pretty good, meanwhile a 5 litre VN has power to weight of about 8kg/KW that would be the hardest 5 litre to beat. A VN group A has a better power to weight again at 6.5kg/KW. But hell with the right money anything is possible.
The VN has a very weak chassis the windscreen can crack from jacking them up, the VP was engineered with alot stiffer chassis which makes the heavier, the VR and VS are heavier again then the VP and the slowest would be a series 1 VT 5 litre.