I have ran O2s for years. First with narrow bands and then with the wide bands. In my opinion, this is a subject that is hard to be only a little bit pregnant in. The varying amount of alcohol affects the reading, you have to really know the carb's circuits in order to know how to make the necessary changes, you need the right carb that has all the changeable bleeds and jets or have a good set of tiny drill bits and taps and all the bleeds and jets to go with those tools. It can be expensive and exhausting to start.
You didn't say whether you were tuning primarily for track or street. They are typically 2 different tunes. The cruise and WOT settings are usually not real hard if the carb is the right one for the job to begin with. The closer the carb is to being right for the application, then the less mods will be necessary to bring it in.
The idle, just off idle, and transitions before the main circuits come in are the real challenges to tune. This includes the emulsions. They overlap so much and there are not a lot of carbs that have screw in bleeds and such in those circuits. Now those circuits are usually not as important on a track car. Pump shot alone can cover up a lot of ills in that area when the throttle only goes from fast idle to WOT. But on the street, those circuits are absolutely critical. Some cars even end up cruising on the idle and transition circuits. That is a real can of worms to sort out and means that major compromises must be made.
Obviously, I don't have any advice on a cheap wide band. I just thought it was important to touch on a few of the issues surrounding using one.
The carb is a 800 cfm Edelbrock AVS2 on a dual plane 440, which is reasonably close to OE application. I am tuning for the street, which as you point out is much more involved than how I would have tuned the thing in my younger years when it was either at idle or I had my foot in the water pump. I'm especially interested to see what's going on from off-idle to light cruise in real time, something I'm not going to get from just reading plugs. I've driven carbureted vehicles for a long time so I'm not expecting miracles. What I am expecting is to have some real data to guide me instead of just a shot in the dark.
The CarterBrocks are absolutely the hardest carbs out there to tune in the transitions. At least for most folks. Nothing in that area can be adjusted without drill bits. While they may be the closest platform to some of the OE carbs, their tunes are not OE.
If you are really going to tackle carb tuning for a street application, you might do well to consider any of the myriad versions of the Holley 4150. Much, much easier to tune for the less experienced tuner and you can get tuning parts at almost any auto parts store. Try that with the CarterBrocks.
And just to be clear, the CarterBrocks are not bad in and of themselves. It's just that their tune is usually farther off base than a correct version of a 4150, are harder to tune than the 4150s, and are much harder to find parts for.
Here is a tuning chart for the CarterBrocks. The fun starts about page 9, and peaks on page 13. Just looking at their tuning charts is a trip all by itself. Good luck with whatever you choose to do.
https://edelbrock-instructions-v1.s3.amazonaws.com/edelbrock/carb-tuning-guide.pdf
