Two electrical questions.

Al
M & H Electric Fabricators makes a reproduction harness for your vehicle. They sell it through Year One for $170.00. They say that the engine/light harness is the same for slant 6 and 383. My assumption is that because the electrical components (Distributor, coil, alt, etc.) are located a similar distance from the bulk head connector that the harnesses are roughly the same. The 318/340 with the rear mounted distributor would use a different harness. I would call year one directly and talk to someone before ordering it.
~Michael