This picture is a straight conversion from the digital file, as I am currently unable to access Silver Efex Pro 2 software on my iMac, which is running the High Sierra Operating system. Unfortunately I have never found any software package that can produce black and white conversions that are as good as those created by Silver Efex Pro 2.
At least I am able to use the standalone Adobe Lightroom 6 that I recently purchased from B+H with my recent film order on the iMac. I reckon it is a case of waiting for a black and white conversion as there is good news around the corner: DxO has acquired the NiK collection and it's upgraded version will be released in mid-2018. I doubt that the software will be free.
DxO is a French company that performs extensive scientific testing on camera image sensors and lenses. The information and knowledge that DxO glean from their tests is used to produce a raw processing software packages called – DxO Optics Pro.This is the original digital file: