Maybe I've become spoiled by using Tri-X for (literally) decades as my preferred high ISO BW film because of the deep(er) blacks and higher contrasts compared to other high ISO BW films like Agfapan 400 or Ilford HP4 (and I'm not even talking about the later Kodak TMax and T400CN)
But I think a much more powerful BW conversion of D800 NEFS, with full capture of blacks, whites and gray tone should be possible, even when only using the 'outdated' Nikon NX2.4.6 software
Enclosed image shot with daylight only, NEF processed as stated above in NX2.4.6, converted in B/W with the BW filter option and fined tuned using the b/w color filter options (the old fashioned way i.e. yellow filter for higher contrast, red filter for 'darker' blues and 'lighter' reds, green filter for better grey tones)