Yeah, I did that too on my copy cat 038, the clone oil pumps I have seen from the hustle site is not exactly high precision tooling inside...
I bought a Hyway oil pump to compare with them and it was like from a different world inside, very nice machining probably pretty close to original specs.
That said if I mount it together some time I'll probably use my modified one that is non adjustable and tuned to nearly empty the oil tank on a tank of gas.
The 038 pump has a dish surface that is angular and rests against the oil adjusting bolt/screw to make the piston move in and out as it turns, if you use an angle grinder or a file to alter the angle on that dish surface you alter the amount the piston goes in and out.
The way it worked originally was that no matter how I set the oil adjusting screw it would use about 10% of the oil tank on a tank of gas, I actually needed to manually oil the bar between cuts.
Not sure how the 660 oil pump is designed though but someone does obviously.
This might not be the response you asked for, but instead of using a pump for another saw that might be just as bad depending on the production batch perhaps you should take it apart and try to understand it first.