Tracy;

That sounds like progress in...at least it sounds like your still data-gathering...but this data will help you understand what is not right, so you can correct it...and in the end, I expect, YOU will be an SU Guru!

My thoughts and questions...

I have not played with a WBO2 indicator so am not familiar with the correlation of AFR to drivability...drivability is really my/your goal (with a secondary goal of optimizing fuel consumption, or at least having it be reasonable, while the car runs well), and most tuners do not have an Exhaust analyzer, or maybe we have it briefly when we have the opportunity to put the car on a dyne...so we tune for drivability, and let the AFR be what it will...you have a different, and unusual situation (which most of us would love to have!)...with WBO2 indicator on board, you have CONTINUOUS Exhaust Gas analysis ...I guess what I'm trying to say it is: What comes First? Typically Drivability...and when we have it, we're happy, and when it goes away we wind up looking for what is wrong and out of the ordinary...in YOUR situation, you haven't had good drivability yet, so your still looking for it, and by having that WBO2 gauge, your already at an advantage in getting there...BUT...Drivability comes first...don't let that indication from that gauge make you crazy!...it's a carberated (not injected) engine situation (with instant electronic mixture correction happening thousands of times a second), so be careful you don't become a total slave to that WBO2 gauge, thinking it should indicate perfect all the time (I question if it ever can with a carberated engine), and always feeling you need to tinker with carbs (once they are set and running well)...

...and I presume you are confident that it is not Ignition System that is holding back engine...hows your Centrifugal Advance?

...so are you saying that for the first four conditions drivability is good and "over 45" it gets bad? How does Lean condition manifest itself? Engine feels like its being held back (even at steady speed) ...popping and spitting? ...poor throttle response?...

Question(s) you need to answer (also what happens when pulling Choke when it indicates lean!):...is it really Fuel Starvation (insufficient delivery to Bowls) or Lean due to Metering Needles...again pull choke when Lean condition happens, if it picks up and AFR indication comes back in range, I expect its the MN...but if this doesn't help, delivery may be insufficient for any number of reasons...blocked line or filter, FuPu problem, blocked Jet Delivery Tubes at carbs, etc.

A properly operating mechanical FuPu should be able to keep up with demand...(Low Pressure) Elec FuPus still will probably need a FP Regulator, and these are typically unreliable junk, so be careful installing an electric FuPu...their output pressure is typically way over the 2-3PSI max that the Bowlvalves can control and successfully hold back...a Manifold Vacuum/Pressure Gauge will have the low pressure range you need to monitor supply from FuPu....

OK on source of SUs, a functional indication of Springs being OK (configuring the carb to be within a usable/linear range under load, or when simply blipping the throttle) is that Dashpot is operating in the middle of travel (and not slammed up against the top or hardly opening)...(for B18/20 they are supposed to be Red).

The videos are theoretical and to help you understand what is SUPPOSED to happen...now it is up to you to correlate that with WHAT is happening...and come up with what is wrong so it can be corrected...

Finally, I always want to know what the engine response is UNDER LOAD...either on a Dyne (where they stick a probe in the tailpipe and tell you for instance "at this load, you're lean, so you could get a bit more out of it if you richened it up here"), or accelerating down the street, or better yet up a steep hill...that is where I use my "Seat-of-the-Pants" gauge...you have that plus a fancy WBO2 gauge to help you interpret what your SotP gauge is telling you...

Good Hunting!