BillboardJS or C3JS Pie Chart Labels Outside w Leader Lines

Question

I have a pie chart built with BillboardJS (could also be C3JS) that needs values shown off the chart with leader lines. I switched from C3 to Billboard partially because it can easily display the values outside of the pie, but I also need leader lines, and to avoid overlap, and neither library seems to offer that.

I need something like this (which uses D3, so I haven't been able to adapt this to Billboard or C3): http://bl.ocks.org/dbuezas/9306799

Here's a sample of the chart I'm trying to build (you can copy/paste it here: https://naver.github.io/billboard.js/playground/):

{
    "data": {
        "columns": [
            ["data1", 30],
            ["data2", 45],
            ["data3", 25],
            ["data4", 2],
            ["data5", 1],
            ["data6", 25]
        ],
        "type": "pie"
    },
    "pie": {
        "label": {
            "ratio": 2.4,
            "threshold": 0
        }
    },
    "padding": {
        "top": 48,
        "bottom": 48
    },
    "clipPath": false,
}

Thank you!