questions on my 71, 454 3Speed.

[patternmakerbob]

Ok guys I finally got some time to start getting the old truck going. After a compression check I am satisfied with 143 to 151 lbs per cylinder and will start the tune up today. However there are a few questions I have.
The motor is a 454 out of a 76 1 ton.
First off where does this black wire go? the other three go to the alternater that was purchased recently.
Second would be what are these things on the firewall. When it comes to electricals I have much to learn. They are not hooked up but nothing works in the cab.
Third, I remember seeing a thread on here about big block headers in the way of the motor mounts. Check out what the dumb*ss I bought it from did to be able to use headers. Uhh, aren't headers to increase flow? Who cares just beat it. Yes they are resting on the mounts. Unless I can find headers especially for this I am going back to stock exhaust manifolds, if I can find them.
Thanks,
Bob