My only advice is this: Play with the FINISHED size of each piece in the block. Size it up by whatever percentage you need (9 in to 12 in is 33% bigger, so multiply each dimension by 1.33). Only add seam allowances AFTER you figure out the finished size of each piece.
You will find that some pieces come to a size which your rulers don't accomodate. Just adjust up or down a notch to come to a 1/4 inch mark.
I usually am trying to downsize blocks for my minis. I realized that I would drive myself crazy by trying to compare the raw size of each piece. Work on the finished size instead.