i have a 68 pickup and i just finished re-wiring the whole truck
i bought a compleet harness kit from painless wiring it was easy to instal and it upgrades the entire system to a modern fuse block and comes with all the extra wiring for power windows, power locks, stereo, etc. it comes with a step by step guide and every wire is labled for where it goes and the harnesses are already separated to engine section , front lights section, rear section and cab section . it comes with everything you need! let me know what you do! good luck
http://painless.r-catalog.com/pg-lkp/ymm.asp