yep story of our build about extra brick and brickwork etc (we had this for removing the side door for the garage since we have the french doors there and wanted to replace the sliding door in the laundry to a 'proper' door with window). And now we have a fair number of excess bricks (which will get used but still!!).
As for the FC above windows you know I was very worried about ours and it turned out OK. However since you have 60cm can you see if you can get taller windows to compensate?