Welcome to the BBC, I see it's your second post.
For the 24V 70#, 8ga will be OK, running 6 would be better. Breaker needs to be sized to the wiring and not just picked cause MinnKota says that's the one to use. If you have to have a bigger breaker and the wire will not accommodate, you will have to rewire with appropriate wire. 27 series batteries will be fine and I can tell you, it's a real trick to configure the back compartment in order to find a way to add the battery. I would suggest a good quality plug and not the molded type that is used by Tracker.
John