adapting horn covers

I just installed a '32 fuel tank in my '28 A sedan and am pondering the best way to adapt the horn covers to meet the fenders. The car has 'gl*** fenders and the inside contour is no where near the contour of the covers. not sure whether to modify the covers to meet the fenders, modify the fenders to meet the covers or a combination of both or maybe don't even try to mate the covers to the fenders. Thoughts, ideas, pictures?
Thanks