I finally removed the oil cooler and the threaded "oil pipe" from the engine. I'm glad to have these items gone. I still need to fully remove the two coolant hoses formerly connected to the oil cooler. A trip to the home store for a few brass plumbing plugs seems to be the agreed on method on plugging up the now exposed coolant circuit.
I did note that the large o-ring from behind the oil cooler looked a bit brittle. It was still rubbery, but it did look to be old and perhaps capable of leaking oil at a high-rate of PSI; interesting.
I have the OEM double-male nipple, the adapter's male-female threaded nipple, and finally the oil adapter installed. The adapter is so shiny and the VDO temperature sender is too very shiny. Those pieces really illustrate the horrific oily mess that the front passenger-side quadrant of the engine really is. I'll update this thread with some pictures soon.
Update: with the oil adapter's threaded nipple screwed fully into the engine the oil adapter itself it loose enough to turn with your hand. So it seems as though I need some type of a shim to push the adapter further down on the engine so tightening the adapter fitting seals the adapter to the engine. This ought to be interesting.