My only reservation would be that I have read somewhere that the siamesed port tends to favor the first of the siamesed cylinders in terms of fuel biasing, leaving the second one on the lean side.
I've read the same - but it was in the context of an I4
The MG Experience where the sequential firing order 1-3-4-2 causes a lean condition in 2 cylinders as RPM rises.
With the distance-between and sequence-of firings in an I6 the effect is likely less pronounced.
Perhaps someone can speak from experience.
regards,
stock49