Canadian Pontiacs used the 261 with hydraulic lifters. If it came with an automatic transmission, it probably had an automatic choke (the C in BC, I think). Didn't the car air cleaners have a cover that placed the filter to the side of the carbs (because of the lower hoods on cars)? At least some of the car carbs were oil bath.
Over the years of 235s and 261s, Rochester BC carbs came with different sized throats and with clamp-on or center-bolt air cleaners. They also came on some years/sizes of 54-63 trucks (maybe forward control and Hydra-Matic-equipped).
Are you looking for a center-post air cleaner or a clamp-on air cleaner (probably center post)?
