Well it turns out that I decided I wasn't drowning in projects enough so I fulfilled a life-long "want" and bought, in the grand tradition of
@JC220's S280, a marginally under-powered Sönderklasse. I bought this w220 S350 sight unseen from MBMarket -
2006 Mercedes-Benz S350 w/63k-Miles For Sale | The MB Market . I figured the price was inexpensive enough and the car is simple enough (base model S-class with minimal doodads) that it was worth the gamble.
I should mention - Ben (one of the founder of the MBMarket) went out of his way to telephone me on the morning of July 4th weekend to make sure that the auction-close and subsequent financial transaction went smoothly for me. Kudos to Ben.
I should mention that this is a one-year-only-2006 USA market car -- a short wheelbase S-class (5 inches shorter than all the other w220s imported into the States). As well, this car uses the proven m112 v6 engine, which I am familiar with in my w210 E320. This m112, though, is the m112e37, so its a 3.7L v6 that shares the exact same bore and stroke as the m113 5.0L engine minus two cylinders. Since its a 5-speed 722.6 (whereas all the other RWD w220s had moved on to the 722.9 by 2006), I have experience servicing it as it is the same transmission in my w210 E320.
Behold the roominess of the engine bay when the engine bay lacks 6 cylinders and two turbos as an S600/S65 might have! You can even see the transmission bellhousing super clearly!
So my kid and I flew into Wisconsin and picked the car up. It was as expected -- the dealer is a highline used car / boat / jetski dealership. They are a dealership. That means they try to make the transaction relatively easy, but they are all about the transaction. Service records, maintenance, fastidious upkeep, troubshooting niggles ---- what's that?

. Like I said, the seller is a dealer. To their kudos, they did pick me up from MKE airport! A couple of issues / niggles but nothing I can't solve with time and patience.
Without doing a single bit of maintenance, my kid and I drove the thing 2000 miles back home. We visited various universities (college shopping) in Illinois, Culver's in Wisconsin, the SPAM museum in Minnesota, lots and lots of Arby's, The Badlands in South Dakota, Wall Drug, THE GSXR in his settlement in Montana, and more Arby's. I had a great time with my teenager as we drove across the country and we talked about stuff. We killed lots of bugs. And the teenager said, after riding
@gsxr's 6.0 liter M119 v8 car, "our car's acceleration is just so.......
frustrating." LOLOL.
Note Airmatic jacked up high for rough road driving:
Note one of
@gsxr's spare engines and how clean the distributor area looks:
