IF you decide to replace the carburetor, then:
A.M.C. starting using the YF on the 258 in 1971.
Federal smog emissions started in 1968, so ALL of the A.M.C. carbs would have some smog calibration. The 1971~1974 carbs will have less smog than the 1975 and newer (the smog requirements REALLY accelerated in 1975).
When smog emissions came about, Carter used HUGE main jets and much thicker than pre-smog metering rods. WHY? Because the wear on the thicker rods is less of a change than with the thinner rods, thus the carbs stayed in specification longer.
The carbs were actually calibrated using the rods.
So changing to a larger jet (the 1971 versions used 0.104 jets) is quite difficult.
So folks have told me they have "sanded" rods to make then thinner. This sounds like a Dr. Goodpliers trick, but cheaper than buying custom rods (which are available).
I do NOT know how the throttle arm would adapt to the Chevrolet linkage.
I like the Zenith carbs used on a G.M.C. 270 for the 261, but they are somewhat difficult to find, and significantly more expensive than the A.M.C. YF's.
IF you decide to keep the Rochester, then the first order of the day is to positively identify the carburetor (some will have a 4-digit number STAMPED, not raised) on the throttle body). For years, the commercial rebuilders grouped the 235 Rochesters and the 261 Rochesters as being the same.
If the carb is correct for a 261, read Jon G.'s blog on straightening castings. And if you wish to rebuild, major overhaul kits are available.
Jon
Jon, you’ve mentioned the Carter WA-1 as a potential Stovebolt carb as YF supplies dwindle.
Would a WA-1 calibrated for the 257 Olds inline 8 be a candidate for a 261 carb? Several different tag numbers of those available at the big auction site, using your website to cross to the application.
A guy would have to live with an auto choke, of course.
