Help! 2 wire Alt convertion question?

uscartool.com offers a kit for charging system upgrade but it wont solve all you problems in a long term sense. You really do have a mess there.
The large wire on the altenater/s should have a rubber boot on it because its hot at all times. One fumble with the dip stick ,etc.. can do lots of harm to your wirring.
You asked about the horn wirring also. Looks like 3 horns there. Should be one or 2 at most.
I understand the need to get it driving again so do what you have to do today but... Next time you go to the parts yard, I suggest you get 99% of an unbutchered harness and replace all that you need to with better original stuff.
Yours isn't so different from many I have seen. Crimped on wire terminals everywhere.
When I upgrade the voltage regulator I'm gonna have to cut a factory connector off the green wire. I'll spend a half hour picking that connector apart so I can reuse it on the added blue wire ( and I will use a length of blue wire ) to back of altenater. Correct colors and insulated terminals make future service and repairs simpler for everyone.
OK so I'm a butcher too. I try to produce steaks and not hamburger LOL
Good luck