If a person wants to go with original Stern parts, here are part numbers:
515-7085-00 Switch & Bracket assembly (rocker power switch and square mounting plate)
https://www.marcospecialties.com/pinball-parts/515-7085-00
Or if you desire to buy the parts seperately, here are the individual parts:
180-5001-03 Rocker power switch only
535-8318-00 Square metal switch mounting plate only
If you want to go all out and make the power switch just like a SAM system, you could use these too:
180-5008-01 Service Outlet only
535-5932-00 Power Box Empty Frame
The whole power box assembly with power cord, varistor, outlet, switch, fuseholder, etc:
515-5360-08 Complete Power Box Assembly (ready to go)