I'd agree on the multipass GTAW for the root. If you are just trying to fill the joint after your GTAW root passes, and FCAW is the way you wish to go, then I would recommend ESAB (the old Alloy Rod guys) "Shield Bright" products. They seem to have a wider parameter range (less susceptable to voltage) than some of the other brands we have used. Toes wet out very well, and gives a nice, smooth bead with easy to remove slag. They make this in numerous alloys. Also, no matter who's product you choose, make sure it is FRESH, and best if hermetically sealed to keep out any atmospheric moisture...you need to keep it dry...a spool may run $500 and if exposed to excessive humidity, you may as well flush the $500 down the drain. Steve