Do you think the opening for your pit is going to be big enough?
Have you considered adding a "work surface" next to it? I am sure you can bring in a table or something, but something permanent might look nice. Just a thought.
Did you factor in the 1/2" of mortar between blocks? That will add significant space difference. I am sure you did, but you also said it was your first time so I thought I'd mention it.
Are you going to make a steel plate/lid to cover the pit for smoking?
Thanks for sharing.