Branded Famos 120 and Superspeed chimneys are so rare and expensive that it is unwise to use them. If you are going to use any of these lamps with a modified Aladdin mantle then a modern, Aladdin heel-less chimney will be adequate. For the Superspeed and Wonderlite burners, the 14 inch high-altitude chimney is the closest to the original.
Famos 120 cp mantles are so rare that it is unlikely that you would ever want to burn one.
If they were, then the best chimney to use would be a bulged type like the original. It also makes the lamp look more distinctive. Early Aladdin heel-less chimneys are suitable, but they are themselves quite rare. The only real option is to get an unbranded chimney from a reputable supplier, but make sure it is guaranteed to be heat-resisting and preferably borosilicate glass.