Need help on bulkhead wiring

Appreciate that tip on the relay. I will have him go through and look but I don't recall seeing this when the car was with me, that's been about 3 years now. Is that interlock in addition to a starter relay or did this replace the starter relay in 74?

That write up by ABODYJOE may just allow him to change the switch if it has to be swapped, I appreciate that link as well.