jon boy jonny,
Using a internally resisted coil is certainly not the kiss of death. Wire it that way and give it a go...you probably won't even know the difference. The terminal is associated with the switch, which is a separate item that is attached to the starter proper to complete the assembly.
You can buy the switch with bypass terminal and put it on your existing starter. If doesn't know voltage from Adam. I am assuming you are going to keep your same 6 volt starter and run it on 12 volts...this is fine and should be plenty durable.
Stuart
