I don't think you pictured the method yet, One side of the piece of aluminum matches up to the through hole mount and is threaded to fit the engine. The other piece uses two short screws that match up with the muffler. Outside of the two are two more holes that one side is threaded so that you can bolt the two halves together to make the bridge adapter.
Instead of using 6 short screws, you use four short screws and two longer screws for the engine.
I haven't had to do it myself yet. But I will eventually.
Like this quick sketch shows
