As Django said above the Thomastick CF30 and CF27 are great G and C wound strings for a low G set up. I have paired them with my florocarbon trebles of choice, Oasis or Worth clear. I never had it strung high G but any string you like should work well.
It depends open the sound you're looking for. I string most of my ukes with Seaguar fishing leader, but found it too mellow on the Multiuke. For reentrant C, I've been using Aquila Super Nylguts for years. They have plenty of punch, which works well when running through a pedalboard.
