I am no expert and am learning also ,the 261 carbs have possibly a bigger jet in the internals ,the car carb from the 261 may have that jet and may or may not be the same as in the Manuel choke carb ,also the 216 carb is the same with exception to the base (the two big bottom slotted screws ) the top of the 216 carb should be the same with the exception of the jet as stated above .I am shire somebody will correct me if I am wrong but you have a good selection of parts to make up a good carb for you engine
