[Aussie_in_MO]

If you've got access to an angle grinder, bench vice, and drill press you can fab up a custom flange pretty quickly from a piece of flatbar (even Lowes mild steel would work).
Bolt holes can be drilled by hand but I find a drill press works better for running a hole saw to cut the inner hole.
I've made several 3" two bolt flanges for various Subaru Impreza projects over the years. Create a pattern out of thin cardboard (manila folder or cereal box) transfer that to the steel with a sharpie, then cut away.