This harness by Painless Wiring may not be an OEM replacement, but is a far superior product that features a modern fuse panel, flashers, relays and as always, each wire has its use printed on it. This 18 circuit unit is for cars with A/C and power everything and is an adaptation of the universal 18 circuit harness designed to custom fit your "Shoebox Chevy" with a factory location mounting plate for the fuse block, special dash and turn signal connectors.
910-20106 Instructions (PDF)