Debbie,
You're right about the seams. I just spent time reducing a block. Subtract the seam allowance first. Adjust the size of the finished piece and then add the seam allowance back in.
I would guess the HST would be cut at 6 7/8". The squares at 3 1/2". The four patch squares at 2".
No guarantees. I've only had a half cup of coffee and it's only 8AM here. :lol: