I have also used
Langdon's dual Carter-Weber carburetors on my 1960 261 (bored 0.060" over - around 270 ci).
They were very well-behaved carbs; however, I think they were "too small" for my engine. I did not get as much response as I hoped-for at cruising speed.
Sweet uses two older/smaller Carter carburetors, I think. They seemed to be a good match for his 261.
I now use a single Holley 94/AA-1 two-barrel Carburetor with adjustable jets (from a GMC 302 engine). This set-up seems to be pretty good - but it does not have the "eye-appeal" of dual carbs.
