Fusions come in 5 degree and 9 degree cants. If your bottom has Vee then go with the 5 degree, and if it has deep concave then go 9 degree. The reason for this is that a fin set on a vee will have added cant due to the fact that the vee panel is already tilted some, so a lesser degree cant wil counter act this problem of ending up with too much cant. a concave(where the fin box will be) is tilted the opposite direction than that of a vee, so this will need a nine degree cant to counter act this problem. Once you choose the box that is right for you, subtle tilting may be necessary to get your desired angle.
I know that futures tell you to shim the jig plate, so maybe you could put some shims under the fusion one to make the routed hole a little bit tilted one way or another.