Got the BB ends put on today. And a root canal
Glued the loose tenons into the slab on both sides.
Put things back together and sanded everything flush. It was out about 1/64th. Took it back apart and remarked everything so I could drill the holes for the pins. Got things marked up and put it back together again. Drilled an 1/8" hole 1" from the meeting edge through the tenons. Then I used a 3/8" spade bit to score the top and bottom of the holes so the final sized drill bit wouldn't splinter the wood. After that I drilled a 5/16" hole all the way through, the 1/8" hole was it's guide. Then I took it apart again. Put an extra loose tenon in the slot of the BB end and used a 3/8" drill to finish the final hole size. The loose tenon was to prevent splintering on the inside of the mortise. Then I elongated the center hole to 3/8" keeping it's width at 5/16". I elongated the two outside holes to 3/8" in the same manner and also elongated them width wise so when the slab expand in the summer there's room for the peg to move.
Glued the center tenon and 8" of the slab in the center. Clamped everything up tight and then pounded in the 3/8" pegs. I did one side at a time and the last side is probably dry by now. I'll see it tomorrow.