pcerra, depending on year and engine (Honda, Kohler) you first want to determine if your 'ignition' is 'ground to stop' (old way) or 'ground to run' (modern 'safer'). If it's the former, like my '98 w/Honda power, you can find a generic switch at most any auto parts store, but look for an "M" terminal for 'ground to stop' built into it. (connect 'M' to both coils)
A common automotive relay/socket can be used to provide 'M' (magneto 'stop') function by using NC terminals and also tying in lo-oil shutdown switch. (can easy show you how I did it) Terramite owners, PM me anytime or ask here for help with either type of T5C wiring setup. t o g