Which Eddy for me?

What trans,what gears, what TC?
With a manual trans;
A short stroke engine with tall gears, works better with a mechanical-secondary carb, due to the lack of TM in the TC. Saddled with hiway gears, and an AVS-type carb, the secondaries might be slow to open, and you will be tempted to speed them up, and then run into a bog or hesitation.
That same engine with a performance rear gear will hardly care what type carb is on it.
The AVS-type carb sometimes has a mind of it's own, delivering the wrong amount of power for a given situation, in accordance with the amount of throttle-opening you have commanded, and has put me out-of-control, more than a few times. For this reason I prefer the mechanical secondary, the power is more consistent.
Autos
are more forgiving,especially as the stall goes up

As to size; on the street,favoring streetability, pretty much any street carb will work, cuz the primaries of even the biggest ones are just about the same size as a big 2bbl. If you choose too small a primary for your driving style, then you will be into the secondaries a lot of the time.
But if the car spends a lot of time on the hiway, then a spread-bore with tiny triple booster primaries is the way to go. I really like those with autos. I love the old small-primary TQs, and their counterpart, the QJs

But really the rear gears are a really big factor. If your engine can spin the tires hard on take-off, or if she lights 'em up at 30mph on the downshift;then not-so-much.

BTW; below your engines peak torque, it almost doesn't matter what size 4bbl carb is on her, cuz the engine will only pull what it can pull.. In other words if the engine can only pull about 450cfm, then only a carb smaller than that is gonna slow her down.And if you bolt an 800 on her, it's still only gonna pull about 450 thru it; that is the mechanical limit of the combo. If you increase the mechanical limit with a cam or heads or compression, and then she pulls 550cfm, then an 800 is still not gonna make much more power over a 550.
And finally; for a streeter with 3.23s and an auto, you are only gonna hit peak rpm once on the way to 65mph, and you'll probably still be spinning into second. If you can do that with a 550, then there would be no point in the 800.