I put the 4 lower strings from a set of La Bella 900 flat wound classical guitar strings on my essentially unused baritone uke. It’s tuned EADG, just like the lower 4 strings of a guitar, or an octave higher than a contrabass. Alternatively I can turn in into an octave uke - GCEA but an octave lower.

It still doesn’t get much use, but it’s fun on occasion.