That R75/5 you are considering has the way coolest of frame mount fairings, the Avon-Air. They are pretty cool even today. I think the R100RS fairing is an indirect descendant of it.
Copper Hill, VA
2007 R1200GS, 1973 R75/5/Dnepr, 1984 R100RS/Motovation,
Gotta get my post count up