The best thing concerning stuff like draw length is to call the bowyer himself. Chuck at Two Tracks is a great guy to deal with, and he'll do his best to answer your questions!
Though I'm betting that the Ambush will work fine since it is both a recurve AND forward handle, sporting the characteristics of a short bow able to take a longer draw.
I have not shot a bow 50", but from what I understand, mostly recurves are available with that draw. Horsebows are usually 56-46 inches and will usually accommodate a long draw, due to their design.
Hope this helps, and if not, at least you got a bump
-SveinD-