clutch safety starting switch

1972 stick duster. raising it from the dead. seems it came factory with the clutch safety switch, none at parts store, not paying $200 off feebay. can't I just use a starter relay from the 69 roadrunner ( parts store only offers the one for auto ) that is for the manual cars.??? just checking to make sure my thinking is correct!!

I have used a mechanical brake light switch for a motorcycle and mounted it under the dash with a spring to pull it.
When the bike brake light switch is pulled out it closes the circuit letting the car start, and the spring stretches so the pedal can travel as far as it needs to.
Personally I hate all NSS's on standards and auto's both.

10 bucks
Universal Rear Brake Light Switch Frame Mounted Emgo Motorcycle Enduro # 21-1222 | eBay