From the photos it looks like the keel is straight along one side and curved along the other, as if the keel assembly was clamped flat during assembly. Is this the problem or are both sides of the centerboard case actually bowed? I had the latter problem which was caused by twisted plywood. I ended up cutting a second centerboard case side that bowed in the opposite direction, but because of the twist I still ended up with an opening about 1/16" narrower in the center of the opening than at the ends. I doesn't seem to interfere with the glued up but still unfaired centerboard. It also looks like there will be enough room for fiberglass and bottom paint. If I were you I would test fit the centerboard before fiberglassing it with maybe a 1/16" thick piece of cardboard to simulate the fiberglass and bottom paint. If it swings freely you should be ok. If not, you may need to extend the sanded edges farther inward to make a more streamlined airfoil shape. You may also need to place a plastic spacer or fender washer on one side of the centerboard pivot to keep the board away from the side that bows inward.
If one side of the centerboard case / keel is straight and the other side bows outward as the photo seems to show, you probably won't have any trouble with the centerboard. There may be a slight tendency to for the boat to round up faster on one tack than the other, but it probably won't be noticable. If you can push the skeg over to where the keel looks fair while you pour the lead, it may straighten out for you. Just a thought.
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