Back when I was doing more engines, the machine shops that we used wouldn't turn down a crankshaft more than 0.020", all I remember is that they talked about weakens the crankshaft, I don't know this as a fact. 0.040" is the most I'll bore a block
You need a better machinist. And a car.
And as Newbomb said opinions are just that does not make it right. And I use gasket on oil pump. In fact I use copper ones.