Tapered lams in ELB's are only worth doing once you are making quad lams so you don't run out of belly! I figured out the rate of taper over a whole longbow and then made that taper in the core. Glued on a parallel thickness belly and bingo very little tillering but it is a bit of a ball ache.
One thing I would say is to try and get a little more outer limb bend for a more elliptical tiller. You will find you don't get that mid limb set then. How do you find wenge for a core? A lot of grain to fill when finishing?