Chris,
For the equipment you describe, I agree with Hedgehog about using the $100 Chevy Duty harness. With patience and care, you can easily install it yourself. It comes with wiring for turnsignals and is set up either for generator or for alternator (three wire alternator; just ignore wires if you have a one or two-wire alternator).
You should also buy new firewall grommets.
By the way, the Chevy duty 55.1 wiring harness is plastic coated but so were the original 1955/1955.1 harnesses.
The CD harness does not have wiring for the heater or for radio (these were accessories back then and came with separate wiring). As Hedgehog suggested, just get the right size wire and do these yourself.
Good luck,
Tim
