Hey everyone, im building up an 86 for show competitions. i had it all down to nothing and trying to put it back together is a pain, esp the wiring!

I have the whole interior wires hooked up, from tailights to the dash. But now i need power for them all. there is a block that goes into the engine compartment where the female connector is inside the car and male harness is in engine comp area. next to the brake master cylinder. This is picture # 1

Anyways i think that this is my power source, the rest of the harnesses looks like its for the engine ( org v6 fi) but im putting a v8 carb in there. Im not worried about engine wiring yet, but just interior. Is this the right harness to power my interior - Picture # 2 ( pic #3 is close up of #2.. are the wires closest in pic the wires that go to the positive battery terminal?) which wires are the wires that hook up to the battery?

Also what about ground wires? do i need to hook up a wire that goes from my battery to the chassis? if so how thick of a gauge and where and how far should i drill the hole to connect to the body.

Any help i would really appreciate. Thanks a lot,
Dan