To use the Go cutter, I think this is the die you would need for the C squares (2 flying geese):
http://www.accuquilt.com/shop/go-fly...ie-bundle.html
There isn't a die for the centre square of the A and B blocks, but you could use the 4" finished (4 1/2" including seam allowances) square, and then add the corners using the HST in the middle of the 55018 die from the flying geese. You would cut off the corners of the big centre square after attaching the little corners, if that makes sense.