I have scrapped the jig I was making- I found a better way to make sure the grid work matches up to the right alignment. I taped the flight deck down to a scrap of wood, with the bottom side showing. The molding of the deck clearly shows the right position where the girders go, with good precision. I am gluing each girder or girder assembly to the spot where it goes. There is lots of glue area on the brasswork where it attaches to the flight deck, so the assembly is getting strong (I also glue each girder to other ones).
The structure so far is looking pretty good. The white streaks is where I used a bit too much accelerator.