I converted this old Portuguese guitar (17.5" scale) to a mandola as it was missing a few of its tuners and had a relatively narrow nut (1 5/8"). It turned out GREAT! I was very surprised with the warm, full sound even with the fairly light strings I have on it. The plain D course gives it much more of a bouzouki/mandolin-y feel to it -- springier and more balanced to my ear. This makes it a great chording/backing instrument as it can fill the roll of a zouk pretty well.
Anyhow, click here for a link to the blog post.
I've also attached a sound clip to the post: mandola.mp3