A quick tip for using 100% VG in the UFS. Add a small amount of distilled water. I use a ratio of 1ml distilled water to 30ml of juice. This is just for flow and should not effect the flavor.
As far as settings, I would use a quarter turn open on the Juice control, then to prime the atty close the air control, take a quick sharpish drag, without firing the mod, till you hear a gurgle. Re open the air control all the way and take a vape. It will probably be slightly flooded. Vape on it till it is where you like then re-close the air control till it is about a quarter to half turn from closed. This should get you close. You will have to teak it from there.
One more thing though. I have never used a HH .357 before, but I have heard that they have a bit of a learning curve to them as well. Might take you a while to get it dialed in. I don't know if you have dripped with one before, but I would make sure you are completely familiar with that atty first and then put it in the UFS. It will make learning the UFS easier if that is the only thing you are focused on having to learn.