Chasmo, glad to hear you got a nice MB. Welcome. I'm no advanced mechanic by any means, but I love to learn about what makes my car "tick". Anyway, I'm not familiar with the front plate mounting on your particular car, a 108 body, but I've read that this body style is pretty common in California junkyards. Perhaps some asking around will get you a proper front bracket with the right mounting hardware. You could also try Partshop on here .. who knows?
I took my front plate off of my 1984 300SD, because Pennsylvania does not require a front plate and I thought the chrome MB symbol the PO had was a bit gaudy. Also, I wanted to have less of a target for police laser and radar. For some reason, it left four holes on the plastic cladding on my front bumper.
Anyway, welcome, and enjoy your 280SEL.