Debur and machine c-sink holes in door and cowl for flush screws.
Install door with clecos, verify fit. I wanted to mprovide a mechanical stop for the oil door so that when it is opened, it doesn't impact the cowling. I settled on two truss head screws, located in the hinge flange, and shimmed with washers to facilitate a nominal gap when the door is opened. These screws will contact the cowling flange prior to the door contacting the cowl.