Honestly I don't think you should unsew & re-do them. Embrace them. You could use your idea of making them a disappearing block - 16" is certainly large enough to do that... are they all different blocks? Could look interesting.
What I would do is make them the same size & put them together - either sew a narrow border on each one so you can trim to the same size OR, just trim to the same size. If they are all squares & rectangles who is to say what the block "should" look like? Some pieces might end up smaller than they "should" but it's who is to say you did not make a creative decision to alter the original pattern?
