Use #2 for the battery to contactors, and to the starter. Use #6 for the main power lead to the busses and alternator if the length is greater than 4 feet, otherwise use #8. You will also need #2 wire or a braided strap to ground the engine to the firewall/airframe.
Thanks Bruce for the help. It was much appreciated. I hope to be flying by the end of Oct. But as you know 95% done is 95 % to go. Seems awfully slow near the end.
Dave