I took on refurbishing a 1978 complete harness just to be able to document it. I put 51 hours into just the main chassis harness. That included building a jig to mount it, creating the labels for every connector, un-taping it, removing it to soda blast all the connectors, remounting it, repairing the small amount of damage to the harness, tracing out every single wire in the harness, created drawings for each and every circuit, created a build sheet (though I can never build new ones as some of the connectors are not available) tested it, then taped it back up. Did the same for the rear chassis harness but that only took about 12 hours total.
I now have documentation at that level for the 64-67, 71, 76-77 and now the 78. I have a 79 harness that is complete but it looks pretty much like a 78 but with more emissions stuff. I may mount that to my 78 board and do a quick comparison later this fall.
My next refurbish documentation project will more likely be a 72-73, or 74-75. Probably 72 as that was when Toyota made major changes to the wiring. Just guessing that the 73-75 are probably pretty similar harnesses.