haha! i have the EXACT same problem.
at first i cut the top of a can to fit in the inset but the screw holes are so close to where the hole is it didn't work.
my other carb that was stock had a filter that was more of a truncated cone shape than the upgraded filter's cylinder shape.
so last night i separated the cone filter. & used my dremel to get out the resin the hold the mesh in. the large circle that latches to the carb fits into that second inset on the upgraded filter. abet with some bending to make the ridge more open.
though i might not even use this since i remounted up my engine so that my carb is more level & the carb doesn't want to fit. so i will try tractor supply & a car parts store to see if i can find a 90 degree bend so the filter will be sitting like an older car does. it will also help with rain landing directly onto the mesh when it rains. it will also help keep the intake out of the how air that is being blown off the engine. i do want to make a couple trips w/o any filter just to help me figure out my 4stroking @ high speed. then before the summertime rainy season in florida i will see about getting one of those louvred bell air covers the use on cars that have triple carbs.
keep us updated on what you do & results.