I've made a pretty similar replica using Flavor West bubblegum and FA lemon-lime. Seems like it takes about two drops of lemon-lime per one drop of bubblegum flavor. Percentages are going to depend on how much VG you use. The more VG, the more flavor you will need. Start low, and work your way up. It's not green, but that's not necessarily a bad thing (I'm assuming it would taste similar to JV's Ecto Plasma).