thermostat housing problem

Other than the change from a standard style to the high flow style, they appear the same and measure the same except for the thickness of the lip that goes in the recessed grove of the housing. I didn’t want to start shaving away metal if there is another housing option out there or even at this point I wouldn’t mind just buying a new housing to replace a 50yr old part but like was mentioned I wanted to get one that fits correctly and not Chinese junk.