I keep checking these threads just to see what the "general level of interest" is on this stuff.
As I'm doing my RB25 rebuild/swap, I'm doing a full tuck on the upper harness (already removed all the wires/box/etc from the engine bay) and using a Tyco Mil-Spec bulkhead connector to separate engine-bay from interior halves. I've found that only 33 wires need to actually pass through the firewall
As far as the interior, I've got a 10-circuit fusebox handling my Accessories and a 6-circuit taking care of Ignition-switched duties, all hiding out under my passenger airbag. On the back side of that plate is the relay logic for push-button start and my fuel pump/fan relays. The car has no body harness, only 12 or so wires running back through the car for tail lights/fuel pump/stereo.
Pics in a couple days.