I could see different bank to bank AFR on a long ram as it basically turns the engine into two four cylinder engines. Getting 2 carbs to make identical fuel curves on what is effectively 2 similar but separate engines would be quite a challenge.
I don't think the balance tube would make any difference to speak of on this as far as AFR is concerned at least above idle.
Kevin
Yep you would be correct, but a single plane intake only needs 1 o2 sensor.
Apparently I thought I was quoting BBM's post. Oops..