Master Shutoff.kill switch

I have a kz1000J2 motor in my little car.  I need a master shutoff.emergency kill switch that shuts down the entire electrical system.  Since the alternator does not appear to be  excited by the like in a street car, can I go to just a 2 pole disconnect switch off the positive side of the battery?  I don't have a complex ignition switch, just a positive lead to an ignition toggle and then on to the fuel pump and ignition.

Below is something I put together for a member with a bike powered buggy. You could do what you suggest but this set up would allow you to crank the starter for oil pressure/compression checks without powering the ignition system