Whew, that's going to be something to see - a big drua with two 50 sq m sails!
I'd use clutches for the hauling parrels. I had Spinlock clutches aboard Tystie, but thought they weren't by any means perfect. My new boat Weaverbird came with Lewmar DC1 clutches, and though I haven't had more than the delivery trip's worth of experience with them, they seem to be better than Spinlock. It seems to be important to get the size right. I'd use 3/8in10mm rope in the 8 - 10mm DC1.