wow nice looking veneers Nitro !! The walnut is very dark so presume that would need to be a natural finish. The zebrano looks very nice too. Id lay the body over both veneers and make sure there is enough for the body and headstock, that may make the decision for you if there's not enough for one type.
I prefer the grain in the walnut looks sick as !
EDIT If you have a look at SimpleOne's (Simon's) 1st scratch build I think his top was zebrano so should give you an idea how it looks. Think it may even be his avatar pic too