If you're interested I can get you in contact with a dealer who supposedly has the antenna down switch. I bought the switch kit from Darryl Waltrip 3 years ago but I understand they are out. PM me if you want the details of who has them.
I believe one of the optional switches that can be placed there is the
on/off switch for the rear parking assistance.
But that's an accessory whereas here is an image of
the full set of switches:
You're interested in 5, 5a-5j
In the C70 convertible the sunroof switch 5d gets replaced by 5g. 5e probably is a switch to turn on the
Driving Lamps if you had them installed.
Not sure what the gas (5h) or transmission (5i) switches would do.