Brian: I would be happy to send you a dozen white birch in 70-75. I have plenty of it. When I was making custom arrows I used mostly ash and birch. I liked birch the best and you can use hand tools on it to do tapering for points and nocks. As a wood it is pretty boring, not much grain to it. But it has nice heft and I had customers tell me that they were able to penetrate deer shoulder blades with them and two blade Magnus. My experience with Sitka is that it is lighter than cedar and I doubt that you will find it in 11/32 for a 70# spined shaft. It shoots really well but one problem I had with it was that is is hydrotrophic...it likes to absorb moisture. It needs to be sealed really well and I found a solvent based polyurethane to work the best. The doug fir and birch, were, to me, very simialr in weight to spine ratio and the fir is very pretty wood and makes a very nice looking arrow. Fir I found to be brittle if it is too dry, but it is a very nice arrow wood if you can get it. And I know you can get that in 11/32 in the spine you want as I have some 11/32 that are over 100 spine. All that being said, I would settle on the birch...which I can send you some to play with.