I purchased some 1.75" thick air dried black walnut planks from a friend of mine for a great price. I was hoping to make a dining table top out of the planks, but one or two of them have a slight bow in the middle of the planks? Slight here means roughly 1/4". The overall length of the planks is around 7ft. All of the planks were run through a planar at some point and are a consistent thickness. My question is what should I do about the bowing in one or two planks? If I had more stock, the obvious thing to do would be to swap them with straighter stock, but that really isn't an option. Given that I attempt this project with what I have, what is the best strategy for coping with the bowing? Note, I don't have much in the way of power tools to help - just a benchtop planar - which of course wont take out the bow by itself. If I use biscuits or splines, would that be enough to align the top so that the top is flat enough to make it work? Would cauls help?