Today I got started on the front vent harness assembly.
The first thing I did was cut a couple of 4.25" segments from some aluminum angle rails, that are 3/4" on each side and 1/16" thick.
I realized that I needed to file the paint from the inner perimeter of the skin piece that goes around the vents, in order to get the vent surrounds to fit through, so I spend several minutes with a half-round file doing that. I took care to always pull the file from the front face of the piece through the back, never pushing out through the front. This helps avoid chipping the paint on the front face.
Using a 1/4" MDF rectangle to separate the surrounds, I fitted them in the skin piece, and then used masking tape to tape the segments of bar in place.
Next, I took the work to the drill press, where I drilled for 4-40 screw holes to be tapped.
I got busy tappin'.
I went back and widened the hole in the rail so that a 4-40 screw could pass through, and countersunk.
With the top vent drilled and ready to go, I taped the aluminum rail to the bottom vent and repeated the process. Note that it is very important to lay the two surrounds face down when determining where to attach the rail. Each surround is different, and they should be aligned along their front faces, not along their backs.
Done for now. The harness seems to be ready to go, but I will likely need to do some very minor hacking on the frame to get it to fit.