Since this is a "math" question I will not be able to help you. However, I want to say that is going to be a beautiful block & if all the others are similar, I'm going to love, love, love that quilt. I'm not quite understanding about the spin of the block & how to cut the fabric but I'm not going to worry about that unless I decide to make a block like yours.
Sometimes things just don't click in my brain like they should.
Can we see the progress of this quilt as you move on with it?