wiring harness

^^^ Exactly.

Start by reading this MAD article which points out some very bad problems with the very core of the original harness strategy

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

then read about headlight relays..........

http://www.madelectrical.com/electricaltech/brighter-headlights.shtml

There are lots of choices on aftermarket harnesses, some of them more complete and way more expensive than others.

The MAIN thing is to fix the basic problems pointed out in the MAD article, to get EVERYTHING fused and protected, and ..... to solve voltage drop issues so that loads get proper voltage.

This means relays "for some stuff."

I used an underhood relay box out of a junk Voyager

http://image.fbt.se/global/images/i...tp/195/bil/lgnr/5374(1).jpg&width=370&height=

but you could mount them in the interior so long as the wire into the engine bay is large enough

Bussman makes the same types of enclosure which you can configure many different ways

http://www.waytekwire.com/images/items/46343FL.gif