There is at least one Holley-Weber carburetor (2300 or 5400?) that is a progressive 2-barrel carburetor that is big enough to not have to be used in pairs on 235 engines. Tom Langdon sells at least one type of these progressive 2-barrels ( 32/36 DGEV
). Supposedly, these are 300 CFM carburetors. Two of these would be too much, even for a 261.
The Carter-Weber 740 (some call it a Holley-Weber 740 ?) is a much smaller progressive 2-barrel carburetor (used on 1600 cc Pintos, among others) and needs to be used in pairs on 235 engines. Tom Langdon sells these in pairs. Two of these are a little too small for a 261, but should work very well on a 235 (which is what Tom seems to usually recommend them for use on).
I agree with Brokenhead regarding trying to rebuild an original Rochester (unless it is leaking from a a pivot-shaft - that is not a simple parts-replacement rebuilt).