I mean the Chev repro vendors, like the
Stovebolt sponser here, basicly "plug and play" [or pray

], using the original layout and connections with very little adjustment needed other than things like the rear wires which will fit the long frame so need to be cut back for the short, and maybe some additional things for updates or options like alternator, which should just be a different "charge system" small harness with the correct connectors
any of the vendors that are wiring specific should have similar, but anything labeled by the number of circuits is aimed at folks wanting to add modern upgrades - you gonna have AC, power windows, power door locks, relays galore, elect fan, etc, etc? that's what the many circuit harnesses are meant for - if you want to put in a modern column with power steering, automatic and column ign, American Classic carries that style harness as well, with the modern fuse panel and switches [and way less than $700]
I've gotten 3 original style repro harnesses from different vendors
like this, all with the right connectors in the right place to fit in just like the original did, allowing good original bits like factory turn signals to be plugged right in - if you want a fuse panel [which would have been factory installed only with electrical options like radio],
the original style is also available complete with correct wires to hook it in, no need for a modern replacement
Bill