I almost finished rewiring my entire 68' with the Autowire kit. I ended up using this kit as well, utilizing the best of both: http://www.madelectrical.com/newstuff/
This may be the way to go, and includes a kit for a newer 10si or 12si alternator w/int reg. It also includes 2 junction blocks - 1 for the drivers side firewall, one for the drivers side radiator support. It includes all the relays needed for hi/low beams on your headlights, as well as a relay for electric fans. I was able to mount the radiator support relays, & junction block in place of the horn relay & volt reg without drilling any holes!
I now have 80watt E-code headlights that work!
It also includes a relay for the starter. (I was able to "hide" it next to the battery) It prevents a constant "live" connection to the starter & you only need one wire to the starter.
Anyway, I now it will put you behind schedule, but it may be worth it. Mark from MAD will answer any questions at length.... It takes time to get the kit though. It was 1 week to ship & he only uses the post office.
I can post some pic's if it would be helpful. The Autowire kit is great, but is very vague about where the main feed wire connects. When I was researching the same problem you are having, that's how I stumbled acros the MAD site.
Some say to use the horn relay as a junction block even though you don't need it for the horn. I would think you could connect it to the starter.