Battery in Trunk Wiring That Exceeds NHRA Requirements
This statement: "The "S" cable going to starter on engine... nothing in this cable to protect it." I didn't know if you meant there is nothing in my set-up, and there should be or, protection is not needed in this cable. If I understand correctly, there is no protection on the wire to the starter because it is only hot when using the starter, and I discuss the 40-60 maxi fuse in the next paragraph.
Using this chart, I'll replace the 1/0 from the large, left side terminal of the Ford solenoid to the cut off, and the 1/0 going from the cut off to the top of the factory starter relay with 6 ga. and a 40-60 amp maxi fuse that I'll put between the left side Ford solenoid and the cut off.
I'd actually prefer to use a breaker, but I don't understand the 12-48 volt rating thing that you mentioned. As to if the voltage range affects the amp rating? If 12 can handle 60 amps, 48 can handle only 15, from what I read. (Ohm's Law thing, I guess.) But I'll only have 12. How does the 12-48 volt range affect an application?