Damn, that sucks. I'll keep an eye out for other possible brackets that may fit. Another option is to have a custom tab welded onto the bracket that you'll be using, though that may not be as safe.
Another forum user installed SRDs', and bent the seat belt tab outward for it to fit
http://forums.pelicanparts.com/porsche-911-technical-forum/853196-mounting-my-recaro-seats-1985-911-a.html