The 5271918870 is an original VC-160 Mark II engine.The 307104235 could well be from a Utility.Still don't have my books here with me so I'm only guessing.No the 125cc cowl won't fit on a 160cc slightly smaller and a different shape.You will see here in this picture the bump for the decompression valve.
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Here for a good time,not a long time.