Output of Schmidt Trigger after a bit more massaging

Here is the turn-on and turn-off points I am achieving against the 3V SLT signals such as +Storage Read. These are very satisfactory.

As you can see, it won't switch to logic high until the SLT line rises over 2.3V and it won't flip down to logic low until the SLT input drops below 0.63V. This is an appropriately large sledgehammer to stomp on the signal noise. 

The output that I have to down-convert in order to drive a CMOS input is swinging up to 3.0V when the signal is on and dropping to a bit over 2V when the signal is off. 

I will simulate a circuit that produces a sharp 0 and 3.3V output corresponding to the 2+ and 3V levels above. Still tweaking that part of the circuit.