hey so the sr and the stock vg are compareable on light tune but the vg can make upwards of 500hp with small mods and just some modified turbos from jim wolf. if i were you id check out jim wolf and see what he has on his site the guy lives and breaths nissan. i know the guys at driven authority in sac cali also do only z32 stuff and they make some other trick things that may help with the swap, good luck and have fun.
the added torq will def be worth the swap so have fun with it.