315 is a little ambitious, even at the crank. Maybe with an entirely new block, a different charger, and NOS? LOL
Also, the block has limitations at or after stage 4 with head flow. Anything after that benefits from porting.
What exactly was the issue with the VR6? If you thought the VR was bad, you'll light the G60 on fire and walk away. It has similar problems, plus about a dozen more. There are only a handful of VR6 problems that will stop it from working, overall much more reliable than the G60. There is SO much more happening with a G60 that unless everything is perfect and like new, it runs like ****. All those vacuum lines, belts, charger, IC and IC pipes, electrical, digifart 1, mounts, the list goes on.
It is cheaper to start with, cheaper bolt ons at the entry level, and easier to work in the bay without special tools. Those are the redeeming qualities of the G60.