273 carb probs!!!

It,s more in this than just the carb.
For example, if you have a dual plane intake it’s possible to have larger carb.
I guess 500 cfm /single plane is equal to 550 – 600 cfm/dual plane, due to the vacuum generated and secondary opening/rpm.
One other important component according to vacuum is the cam. I’m not able to give a formula, but a sharper cam generates more vacuum.
So, if you put an Eddy 600 on a single inlet with a mild cam, there will be problems with the vacuum and secondary opening.
But if you use my recipe, Eddy D4B intake + Comp cam (duration @ .015 270/270, duration @ .050 224/224, lobe lift .313, valve lift .468/.468, lobe separation 110) the Eddy 1406 will work very nice on a 273.
My do it.