wiring question

what size wire should be run to all the different things under the hood. i know ohms law so things like lights i can figure out. i got a wiring diagram from this site and i am going to rewire my jeep 66 cj5 with a v6. this all started when i replaced the battery cables and started poking around looking at wiring. example there is a cable that goes from the battery to the starter then from the starter to the alternator what size should that wire be ?

 

I would make that one an 8 ga wire. If you up-grade to a 100 amp delco alt in the future (you may already have it) that is what you would be better off having. If you are running an AMP gauge then nothing smaller than 10 ga there. 12 ga will be good for all but head-lights and ignition. From the H-light switch to the dimmer no.10. From the ignition switch to the ballast use no. 10 and ballast to coil + use no.10. You may think 10 is too heavy but not after you begin to upgrade will you kiss yourself for doing so.