k&n panel filter fit

hi guys got a k&n air filter to fit to my carby m750 and am having issues basically it wont fit! the fins are deeper than the standard paper one and it wont go in and close without cutting the airbox lid. now i have got one thats cut already and will fit with the k&n but surely this isnt how they are intended. i dont really want an open airbox as surely i will have to rejet the carbs.
help appreciated
james