Gorgeous car, ekrupa2. Especially like the paint scheme.
On the harness mount:
Remove the wheels and squeeze up in the wheelwell and between the rear firewall and the trunk wall, there is a horizontal frame member, maybe 1 1/2" square. Attach to the top of that member, bolting all the way through it. Don't have any pics, but have seen it.
I'd send another email to SCOF at
superformance@yahoogroups.com. They can be a grumpy group but have the best technical knowledge anywhere. Unbelievable the things these guys know. Several of them make their own upgrade/replacement parts. But they don't take kindly to novice questions so try and come across like a wrencher and not a waxer.