There are several aftermarket electrical vendors that have these plunger style switches. It looks like it a standard style screw-in switch that they mounted to the aluminum plate, then screwed the plate to the door jam.
Painless Wiring, Ron Francis Wire Works, American Autowire are a few. I’ll bet yours is available at a local jobber that has a well stocked Motor-Mite or Help! inventory too.
I’m 6’3″+ and 260 lbs. You should see where I sit in my replica!