Hey Drikko, here is a picture from my SFC1000 from 1987. The black object of the picture is the airbox, thus the front of the bike.
Don't know if the layout from the RGS is different with the SFC but mine has the negative pole at the right side. It's a bike with only 17.000km so I think everything is original but maybe the former owner has change the layout of the wires when he bought a new battery.
grtz.