Does MO have smog testing? If not, Im not sure if Id be that concerned, at least until you get a CEL.
You bought a 100k mile van that was on its second owner. I dont know the history, it might have been a rental before that. If so, it might have only had one oil change at 10k or so, maybe not even a second until it was sold! Who knows... The good news is that you have lots of records from the past owner, and you know that these engines are intrinsically oil burners.
My 91 BMW became an oil consumer as it went past 150k or so. It was a higher RPM engine though, and I could never place where the oil went. It didnt leak it, it had to have burned it, but it didnt smoke, and passed dyno smog tests. I think it had to be related to lots of highway mileage in a car geared with a 4.10 rear, so it wa always cruising at high RPM. That was, I guess, in its favor.
If the van smokes bad, thats one thing. If it smells bad, thats another. If it needs to pass a hard smog test, thats yet another. If none of those are the case, Id consider the fact that you got a good deal on what looks like a nice van, pick a good oil that is likely to cause minimal issues on the cat (lowest SAPS), and then run it. Chalk up the quart of oil to the money you saved buying a used car of that vintage. If you run a conventional low SAPS oil, what is it going to cost you? $20 over 5000 miles? Since this is an older engine, and WM SuperTech is well regarded as being "good enough", then its what, $13 every 5000 miles to feed it oil? Not bad in the end, especially when some folks believe that running some TCW-3 or similar oil at a low dose is good for these older engines. I would think about running a good PEA cleaner each oil change, in case deposits are forming, but again, whats that if you shop around? $5 every 3000-5000 miles? Not a huge deal considering that you got a good deal on a nice van. I would be sure that if you decided to go with a high mileage oil (not sure its really needed), that you ensure that you dont get one with boosted ZDDP, as that will help kill your cats, and thats not a great idea regardless of SMOG testing...
I would still run the compression test, and consider doing a soak, be it with MMO, Kreen, seafoam, etc. It may or may not help, but baselining the engine's health, and potentially getting insight into if a cylinder or cylinders are potential issues would be helpful including for your peace of mind. Have you pulled the plugs yet?
Good luck!