Mine, a '04 Koga WTR is not really a conversion, they built it up like this,
see on this site: http://www.cyclofiend.com/working/2008/wb092-robertclark1008.html

I made a few component changes,
additionally some have been made since I submitted the photos
saddle, rear bag, different HB bag...

Were I to strip the bits off and get a new frameset,
the sliding dropout would be fine with a single speed , or a non Rohloff IG hub.
I happen to need more ratios for varying terrain and weather conditions

with a 40 mph headwind you need a lower gear.