I do some installs of beverage equipment.
Usually beverages are around 5 to 1. The cup I have has the ratio printed on the side.
Are you sure that Coke doesn't also come out for regular service?
It may or may not say the ratio on the box of syrup. I can't remember offhand who does and doesn't.
This is it: http://foxxequipment.com/parts.php?id=6873