Mr Norms GSS Owners???

You could try contacting the Mr. Norm's Sport Club- although the current iteration caters to the newer cars, I'd be willing to bet they could give you some info on any current registries for the classic stuff.
MrNorms.com - Sport Club
MrNorms.com - Vehicle Documentation

A friend who was close to Norm is compiling a registry of sorts. I hope to talk with Larry (owns all the Norms paperwork) to sit down and list all the VIN numbers we can find. Mostly looking for FABO members who may have GSS and M code cars.