right, snowflake spoke pattern but with a drum brake as opposed to a disk. gs125 runs iirc an 18 inch rear snowflake with a drum, prettty cheap to come by. also, iirc the older gsx250/400 twins had a similar setup. i once had a gn400 single that had the back wheel collapse, broken spokes, cos i was pulling a sidecar with it and it couldnt hack the side loadings, so i fitted a gsx400 rear wheel, as i recall it was just a matter of changine a wheel bearing to make it fit on the gn spindle. if it were a disk rear that you wanted, ive literally got a pile of snowflake pattern gs and gsx rears in 18 and 17 inch sizes, drum rears are a bit trickier to source, but i think that gs125 will be ok. that bike pictured also has a gs125 tank and sidepanels fitted so its a fair assumption that its owner bought a complete bike to build it up, and used the wheels too.