Just wanted to update this thread since I have had my overhead console/cab shelf done for a while now. Some may have seen it in my build thread, but for those searching for how to do this here is the process and pictures of mine.
Everyone's suggestions and pictures were a huge help. I started this like everything in a cardboard form. Luckily I had the stock headliner out so I could use it as a tracing guide for the windshield side. After transferring this to ¼ Baltic birch I was able to do an initial test fit in the cab with the stock headliner in.
-Then I located and cut out openings for the sun visor mount and center clips. The visors can't mount directly to the wood since they need to be held at an angle that matches the original orientation to maintain full functionality. So I cut an oversized hole and used an odd-shaped piece of ¼ BB to space the visor down. You can see that I clamped a 4 level to the shelf while doing the test fit to get everything all lined up and fitting correctly.
-After getting the visors located correctly I was able to get my final dimensions all figured out and cut.
-I then added the vertical ½ BB supports which are cut to the taper of the headliner.
-After that, I started on the front face of the console. I used ¼ BB that was pushed tight to the curve and then scribed to the headliner to get a tight fit.
-After getting the face figured out I worked on the location of the overhead switches and where I wanted the openings to be located. I have enough room on both driver and passenger sides to have 3 22mm pushbuttons, but as of right now I am only using one location for the overhead map lights.
-Clamped it all up in place and then pulled it from the van to do a glue-up of the front face. I unintentionally made it a much more complex curve as it has a few flat spots with connecting curves and the front face goes from being perpendicular to the shelf to more angled in the center. Wasnt an intentional design choice, but I am happy with how it turned out.
-Then it was back to the van for a final fitment check. As of right now, I am only using factory mounting points, and it seems to be plenty strong for what we are intending to use it for. It is held in place by the center visor clips that have long screws pinching the shelf to the van frame and then it is also pinched between the headliner and the A-pillar trim on the sides. Still have a few more things to do before upholstering but I am pretty happy with how this came together.
-I also added some small 1 overhead lights that I referenced above as overhead map lights. I saw this idea in a few pictures from SMB West's Sportsmobile Classic build and thought it was a great idea so I added it to our list.
Hopefully, this can help the next person looking to build one of these!