It was a challenge to figure out how to drill the aft end tabs of the thin, inner lip which forms the inside surface of the groove. I ended up drilling acouple holes in the flap actuator tunnel, then drilling through those holes. The holes are required, anyway, because the screws which get installed here are going to protrude slightly through the flap actuator tunnel.

I also drilled and countersunk for a couple nutplates to attach the forward flange of the pushrod tunnel to the floor plate.

I really wanted to drill all the holes around the top edge of the center arm rest, but I haven't received the soft rivets I ordered yet in order to prove them out. Not wanting to put the cart before the horse, I decided to cut the hinge for the lid, remove some hinge eyes in the middle, and make a little hinge pin retainer.

Here's roughly how it'll look all installed.