I have used original single-barrel Rochesters (matched 261 carbs) on a 261 engine and it ran as well or better than the dual two-barrel Carter-Weber carburetors I am now running.

The only way to really know what set-up is more fuel efficient is to run a test.

The only way to know what extra power might result from two carbs is to measure the hp.

I think that I have noticeably more power with two carbs. I have as good or better fuel economy with two carbs. I think that two carbs looks good (and, I think that two original Rochesters with original air cleaners looks the most interesting).

Tim