vg30e will fit in a datsun 510....so it'll definately fit in an s30 chassis. you can fit anything in a s30 chassis. if a v8 fits in it with room to spare then why wouldn't a v6?
i've done a vg30e swap into an 87 mazda rx7
he just used the v8 mount kits and got a custom driveshaft. i'm not saying you can go and get the motorsport auto $250 v8 mount kit and it's gonna bolt right up so don't waste your money yet. do some research on
HybridZ
for the wiring i have no problem making you a plug and play harness if you like, pm me for details. i just finished an rb26 into a 350z with working guages etc, pics are in the "z owners step in" thread
anywho pm if you need me
Dave