Yeah the VQ30 block is definitly not as strong as VG30. IIRC the VQ30 can goto around 560 BHP then the block splits. The VQ35 block may be more strong, im not sure. I believe JUN racing has built a 750 HP twin turbo VQ35 race motor for a 350Z, so thats probally true. As far swapping a VQ35 block its been done by one Maxima guy I know of. He put a 2k2 Maxima VQ35 block into his '98 Maxima using VQ30 cylinder heads and manifolds. It may be possible to get a junked 350Z and swap the block with VQ30DET heads and manifolds.