You don't need another motor. Just get a turbo kit for your VQ30DE. Look on Maxima.org for a member named 'Turbo97SE,' aka Nigel Cheung. He is also on Turbomaxima.com. Nigel has dynoed 267 fwhp @ 4 psi and 370 fwhp @ 11 psi using stock engine internals and transmission.
The VQ motor has iron cylinder liners as well, so it should stand up to even more boost, once the compression ratio is lowered(10:1 stock).