You can change the filter, but you can modify your stock snorkel assembly to make it fit. A few different methods have been applied, but all I did was trim down the vertical portion where it "slides" over the top of the carb. It requires removing the stock clamp - but not much more - and then adding a set screw thru the remaining portion of the vertical portion into the top edge of the carb.
I think there is a file describing this surgery as performed by Wayne, where he put hold down screws thru the top of the snorkel assembly. It is very clean looking. I went the way I did to try to retain as much of a stock look as possible.
Retaining the stock snorkel has the side benefit of supplying slightly cooler air to the carb, as opposed to a rectangular "free-flow" type of filter element.