I'm guessing the lancewood, is a native NZ tree(wikipedia: Pseudopanax crassifolius, the horoeka or lancewood, is a New Zealand native tree belonging to the family Araliaceae)?
The lancewood used by bowyers in the 19thC is from S.America, Carribean region.
We have a couple of woods we call lancewood in Australia, and they make good bows. They are actually very dense desert acacias, look nothing like the original lancewood timber.
I have no idea about your wood's properties. I think I have heard of other NZ bowyers using it successfully. I'd probably start off with another flatbow, selfbow to find out if the timber has any idiosyncrasies, like chrysalling, brittlness, or excessive set. Its a gamble to back one with boo first, before you know if its resistant to chrysalling.