I clamped up a scrap tooling plate in the mill vise and used a couple of small clamps to hold a 3/32″ sheet of yellow brass on it. I then laid out a 1.375″x0.600″ grid of 15 flanges, drilling a clearance 
hole in the brass, and tapping the tooling plate below with a #6-32 tap. Once some #6 screws were tightened down, I was ready to roll.
Archives
Hodgson Part 074, Intake Crankcase Mount
I rough sawed some 0.5″x0.9″ blanks from some 1/8″ 7075-T6 aluminum plate for the mounts. I decided to go with aluminum instead of brass since the intake pipe does not get soldered to this and I thought aluminum would look better next to the aluminum crankcase.
Hodgson Part 075, Flange Gasket
Once again it’s McMaster-Carr to the rescue. I ordered a sheet of 1/64″ +400°F aramid fiber gasket (McMaster P/N 9470K36). Now the only problem was how to cut the gaskets.