The fiberglass mounts are a bit larger than the aluminum ones they used to supply. (the glass ones are better)

Generally on the 4*40, the top of the mount will ALMOST touch the curved sheeting on the forward deck.

Reallly... you won't be able to have it far enough off up and down to matter. There isn't the room on the firewall to get it off enough to noticeably bother performance. (there's only room to get it about 1/4inch off to a side... maybe 1/8 inch high... maybe 3/4 inch low... you'd have to try to be wrong.)