Too much O@ that is a new one, usually they fail because of too much HC's. I don't think it is related to not having an O@ sensor either because the PO removed it or because it never cane w/one. when O2 sensors fail, the system runs rich, not lean as your test shows. The 22r's have an air induction valve that could be stuck open, allowing too much O2 into the system.

Other than failing the test, how does it run?

More than tread lightly. Leave it like you were never there, nor anyone else.
'90 X-cab 4.88's 33 BFG AT's, rr ARB, Headers, Ignition upgrade, cold air induction.
'91 X-cab 5.29's 315's BFG MT's, rr ARB, custom bumper and flatbed