What is the most HP that the vg30dett can safely handle on a stock block? Boost pressure PSI?

I would kind of slow down your list puts you at about 450 hp at the rear wheels. Make sure your using a single piece drive shaft. To make more than 500 engine hp your going to need better pistons and connecting rods. Stock blocks get into real crank shaft stress and oiling of the main and rod bearing issues at more than 17 psi boost. Your list of parts does not have a larger oil cooler or Howe Radiator And have you already installed Dual Z1 larger inter coolers? And what are you using this car for track, drag, drifting or just fun? I have blown up plenty of Z32's.