<
Today meter consistently fluctuated between 18.2 and 21.5 with both vac hoses connected,
with hose to fuel regulator disconnected between 21.5 and 23.6 and with hose to SOV disconnected between 21.7 and 24.4

Are these vastly different (47-53 vs 18-24) readings correct or am I doing something incorrectly?

Considering my reading (if correct) is not near the .9 for Rich, can I assume the o2 sensor needs to be replaced?>>

These are the readings I an not sure about..the other without the decimal [47-53] I understand, but not these, as you have a decimal. [ 21.5 . 23.6, etc ??]

Anyway, a couple of pointers for you..
As you are using the engine for rich/lean generation, you MUST disconnect the green wire feed to the ECU or the ECU is going to try and correct your engine rich/lean inputs. Do you have the green wire still hooked up when testing the 02 output???
Also, you want to try these test at 2K.