Not sure if you've considered it or not, but if you were looking at Painless, you may want to look at American Autowire's Classic Update kits. It's like the Painless, in that it is a modern style fuse block with extra circuits for modern upgrades.
Unlike the Painless, it comes with pretty decent instructions, factory type connections installed wherever possible (for example, the wiring for the neutral safety switch is long and does not have plugs, so it can be used in a manual, column shift auto, or floor shift auto), and it's roughly bound (zip ties, not non-stick tape) and configured to mirror the OE harness. Also, at about $450 for all new wiring front to back, about half what an OE replacement style plug and go system is.
I am finally getting to the wiring in my 69, and I couldn't be happier with the AAW Update harness (well, okay, if Ray and Theresa from AAW came across the river and put it in for me, I'd be happier
). I hung the AAW side by side with the OE, and they match up really well. The Update also has a set of wires for modern accessories like power windows and locks, power seats, electric fuel pumps, electric fans, engine computer, Vintage Air, etc.