Here it is! The vise chop is quite heavy, much denser and harder than the southern yellow pine used for the bench.
I cut the pinboard from a cutoff for the bench laminations. I planed it to just proud of the thickness of the mortise that was already in the vise chop. I then carved a tenon in the end that matched the mortise. I drilled pinholes spaced 1/2" apart from eachother along the board's length.
I chopped out a big hole for the vise screw, and another hole for the pinboard; both benefit from a little bit of play.
I think I'm going to wedge this tenon into the vise chop once assembly time is closer.
And here's a view from the back. The big nut came with the vise, I plan on screwing it into the back of the leg right before assembly. I entertained thoughts of recessing it into the back of the leg, but such an overcomplication is not necessary. The vise screw still allows the jaw to open quite wide.