Been doing some research into Xs1100 racebikes of the time. I came across this grainy photo of Ron Boulden and Stephen Gall and their 1981 Standard they raced to third place that year.
^that's not your bike, is it Christian??
^ and an equally grainy pic of the bike in the rain.
Anyways, I did a bit more scouting around and came across this book that was mentioned in an old thread on the netrider forum
which I hadn't heard about before. Sounded promising, so I looked on the bay and ordered one.
I'll let you know what it's like and I'll try to scan (or photograph) any good photos and post them up here.
Here's the book details FYI
"THE CASTROL SIX HOUR PRODUCTION RACE.
1970 - 1987
By Jim Scaysbrook
Publisher: Renniks Publications Pty Ltd . 2008
Description: A brand new hardback copy. 240 Pages.
Black & White and Colour Photos Throughout."
Should make an interesting read, at least.