I have a small collection of Scottish tunes for the 18th century English guitar on my site:

http://www.purr.demon.co.uk/jack/Music/ScotsGuitar.abc

I guess tuning a conventional guitar DF#Adf#a would sort of work for that, though the lower pitch would lose the incisiveness of the original.

Rob McKillop has more tunes of that sort on his site, mostly for DADGAD tuning.

The conventionally tuned guitar is not much use as a melodic instrument for any kind of British Isles folk music. Any strong accents get ironed out into a stream of soporific torpor. There isn't any way to fit in the sort of stuff that flamenco uses to really exploit what the instrument can do.

The absolute clueless pits has to be some of the stuff John Renbourn used to do (I haven't listened to him in years, this would have been the 1980s) where he tried playing dance tunes with fingering patterns that put the open strings on unaccented notes. It sounded quite bizarre and totally buggered up the dance rhythms.