Maybe a little but not too bad. Dodge did something like this to make the Super Six in the 70s. Put the 2 bbl off a 318 on a slant 6, changed the advance curve and made the exhaust 1/2" larger for an extra 10HP.
Note my they don't. If it will bolt to the intake it will work. depends on the intake on the 6 and which rochester it is they had two different bolt patterns bib and smell.
I never seen an intake for a two bbl only ever saw them for stock single RochesterB, 3 bolt carb tripower manifold and this one for a 4bbl: But that doesn't mean they don't exist.
So 2 x 1 > 1 x 2 ??? Just joking around, the distribution is better for two 1 bbls. As to orig OP question, if the carb fits it should be OK, most inline 6 are kind of stock undercarbed anyway.
sorry for the bad spelling, was in a hurry this morning. I have a transdapt 1 bbl to a 2 bbl adapter just doing some playing around. thanx for the info.