Looks like my dimensions weren't that far off. Those images I posted were obviously stripped down in detail, purely for dimensioning purposes. Kiddo has at least two threads on the AC III hawk, all with good reference pics that would be useful to you for getting the correct curvatures.
One thing I would say if you are doing this, is get the eye correct (Where the haft connects to the head). Most of the ones I have seen have either a round or oval eye, where it should be an elongated hexagon. It's cross section is very similar to this shape: