I recently put TI flat wound guitar strings on my Burgin 23" scale Shanghai octave mandolin (.012, .024, .033, .044). I use TI's on my Lyon & Healy, for which they are perfect, and I was curious (although hesitant) about them for my OM. It was a fortunate experiment because they are SUPERB.
There have been lots of threads about TI's on standard size mandolins, but I haven't seen much regarding OM's. Folks seem to love them or hate them. I play only classical music, no Bluegrass, and for that purpose and my taste these TI's are tremendous. They are called Plectrums and the product number is AC112. Bit pricey because you have to buy two sets to get the string pairs - but like other TI's I suspect they will last 3-4 times longer than most traditional rounds.