I use FAJC all the time for priming. Read the label on can, as brands vary, as to amount of sugar. Look at carbs, 28 grams to 1 oz sugar, mine has 170 grams of carbs to whole can or about 6 ozs sugar, so I would prime with 2/3 can (8 fl oz) instead of 4 oz sugar.
From experience and plugging...