Nice set of options. $10k was a lot of money back then for a car.
I am sure the option group G03 is one the "S" Appearance Group ones.
If you haven't yet poped over, the guys over at the Early 911S Registry BBS (
http://www.early911sregistry.org/forum/index.php) may be able to better tell you about the options included in Group G03.
Somewhere on this site, I think it was Grady Clay who posted a series of posts on the steps to safely revive a car that has been stored. You might want to look for that as well.