I agree 19mm bars, we use a x or ET base plates. Remember Epic needs raised up 11.8mm to align lens centre correctly. Stainless or good carbon bars work fine.
If the bars are very long with a heavy lens you may also need an extended wedge plate which the front of the bars can rest to provide additional support.
We have a small 19mm to 1/4 20 lens support on to which the lens is supported on to the bars.