A horn sinew composite should not be made with a 1/4 sawn core.
Wood is less laterally stable when 1/4 sawn as opposed to flat sawn - this WILL make a difference in the finished bow.
A kiln dried board will be hard to bend to the shape you want.
Green maple is what you want. Stay away from any ring porous wood. Diffuse porous wood is necceasary due to it's uniformity.
Trust me on this one
Have you bought Adam Karpowzi's book yet? I strongly strongly recommend this excellent book. Once you've got this it's likely if you follow it to have sucess first attempt.....without it....well good luck!