I will try this, thank you.

Yeah, I used the obsolete LEDs in the simulation since the ones I am using aren't in LTSpice. As for the actual red LEDs they do turn on, but the current isn't right.

@BruceAbbott I'm using an LM358N Op Amp.

@james I don't have an oscilloscope, but for what it's worth: I did some more measurements today & I get mostly-correct (matching prediction) #'s if I put one multimeter to measure Vin while the other meter does the actual measurements, but the BJT burns up after a few seconds despite operating at less than its max ratings. I placed a 3 Mega Ohm resistor to try and mimic this meter effect but it didn't work. In any case, it looks like I'll at least need better heat management or a higher rated BJT.

SO hang on, pg 25 seems to say that I need to wait >37us between each 4+4 (8 total) bit inputs, but is ambiguous about whether I should do anything with the "E" input or how long the delays between each set of 4 bits should be. On the other hand, 27 says I need to Delay > 80us between 8 bits in total, but specifies that I should use "E" to signal each set of 4 bits? SO: 1. Do I use "E?" 2. Should the larger delay btwn each 8 bits be 80 or 37us?

What if I have other components that can't all work off of the same Voltage? (Ex: I have an Oscillator that can only take a maximum of 3.63V and decoders that need at least 4.75V to function.) I guess could just use a different PSU for each Voltage, but it seems like there is a smarter way to do this that I don't know about.