Steve: I took a copy and tried something, I didn't think that it would work, however it did. Not bad with the image posted would be better with the full file. I use NIK silver Efex Pro 2, I applied it to the shot and used the Grad ND(EV-2) preset as a starting point and a B&W also works with the image. It it not to often that both a colour and a B&W both look great, I though still lean to the colour image, but damn that B&W.
Cheers:
Allan