My dumbass bought the wrong big bore kit

My dumbass bought the wrong big bore kit

This is the underside of an aftermarket big bore cylinder for a little Chinese scooter engine with the aftermarket dowel pin on the left and the stock pin on the right, and the only issue is that the stock crank case uses the 10mm dowel pin while the goddamned sucking fucking big bore scooter kit uses the smaller 8mm dowel pin. The son of a bitch bastard hoebag that sold me this fucking paperweight doesn’t take returns, and I’m not prepared to spend any more money on this piece of fuck-made in Taiwan shitbike by buying another cylinder that might fit. Anyway I’m asking if anyone has any great ideas or knows where to buy a specialty machined pin online I can buy that is two different fucking sizes at the same time. Maybe I could I drill the cylinder dowel holes bigger but how can I do that while keeping tight tolerances?

Thank you r/smallengines