Charging system and other wiring change help needed

Cut my first 2 wires tonight for the battery to solenoid and solenoid to cut off switch. I am going to take them to the local parts house tomorrow to have the correct ends crimped on. I decided to go with the ford solenoid with a 2 post cut off switch mainly because I already had those parts. I do realize I will have a hot wire coming from the alt into the trunk. Right now I will put that wire into a sheath for some added protection. At some point in time(before I go racing) I will change this and go to a 4 post switch but I want to try to fire this up in the next 2 weeks.
I ordered 25' of 8 gauge wire today for the alt to solenoid. Nobody seems to carry 8 gauge! I'm hoping that will be heavy enough for my needs. I am only running the factory alt which im not sure how many amps they put out in 66. (up to 60?)
Cant work on the car tomorrow so I will be back at it on Thursday night. I want to get the trunk into the dash area completed then move forward. Im sure this is going to take me at least a couple of weeks.
Thanks for all the help and advice so far. Please let me know if I am doing something that is not going to work or I should change.
Rod