Spark plug is at an angle, on a series 70 engine, that indicates 125cc.
There is a bulb in the cowl that shows the decompression valve, making it MKII or MKIII.
The sticker is also a MKII sticker, so the serial should point to 1971-1972.
You will find the muffler clips attach to little pegs, as the head is not bolted to long bars, the cylinder is bolted direct, like earlier 125cc's, and the head is bolted into the cylinder.
