Yes, I say it's running rich but not nearly as bad (no smoke) with the computer changed

Once it goes into closed loop, it should figure it out. Does it?

Figure out what? And at this point you can smell the richness in the exhaust however the only thing coming from the tailpipe now visually is oil. If your meaning when the computer goes to close loop it doesn't run any better or worse.

In that case, the question becomes: IS the PCM going into closed loop?

That's a good question how can I tell without a pricey obd1 scanner? All I can assume is that it's good bc it came from a running truck?

Also just drove it around for a bit no issues other than oil smoke, however now it seems as if it's running lean. I know this thing needs the plenum changed as there's the telltale intake full of oil. And I know that also a leaking plenum will cause a lean condition.

And it will eat O2 sensors, and catalytic converters for lunch. Not to mention eat oil like its going out of style. Need to address that.

Yes, it's burning a quart of oil every few days

Think I would be real tempted to do a compression test on that motor before spending a dime on it......

327k on the clock