Ok...I'm looking at this another way now.
I started with 36-10" blocks and a border.
After that, I cut them, and ended up with 49-8" blocks. Finish size 7 1/2".
So, if I do 7 x 8 = 56 plus border, I should end up with 8 x 9 = 72 8" blocks (7 1/2" finish) yeilding 60 x 72...I add my 6" border, and I should have 72" x 84".
That should be good...I think.
If not, I can always add another border!