Well, if the wood is breaking apart under sanding, then I would give up on the history and go with new. There is also a pre-stain wood prep that you can apply that will allow your wood to accept staining better. That, and good sanding will get you a nice finish. When you are picking out wood, if you want it to look more original you can try to find slats with minimal dark grain and knots. But, if you want to stain a little darker and show off the grain then go for the opposite. Both look good. It is just a matter taste and style.