West Coast Metric has wiring looms for sale.  They seem to be gradually working their way up to providing more complete products depending on the age of the BUS.
They recently came out with a 'Main Wiring Loom' for the 1970-1971 Bus, which
covers the area between the fuse block and the engine.  It lists for $155.00.

Their toll free number is: 1-800-247-3202

They have shit-loads of good stuff for the air-cooled, steering-wheel-holding,
passenger.....

Wolf