Or you can just buy an ignition switch with a key, or have a key made.

I have always found it more convenient to rig an ignition with a cheap toggle switch (12v 15A) between battery feed and ignition RUN terminal or coil positive. Then use a 12v 20A momentary on pushbutton switch between battery feed and ignition START terminal.

If you run the ignition switch to coil positive, you won't have the resistor wire so points won't last long, but if you're just shuttling around it'll be fine. I drove a car for a couple weeks rigged like that, until I could find and modify an appropriate wiring harness (before repros).