I don't know the brand of wire(Lincoln wire likes a bit more heat than ESAB for some reason), but I'm thinking you'll need to be somewhere around 27-28volts at 280amps+/- for the flat, maybe just a smigit less to fine tune for the OH....but for running vert up, I would back it down just a bit more to around 25-26 volts at 225 amps.
Keep your stick out around 3/4", measured from the contact tip to the material...(not from the nozzle). Gas flow around 35-40 cfh should give you good coverage.
This should get you somewhere in the ball park, and then fine tune it to get the least spatter and still be able to control the puddle. Remember...Big ole spatter balls = voltage too low or WFS too high so adjust accordingly. Take your time when you get towards the cap, it will be hot and very fluid, so don't let it fall out on you...this is only 1/2" material, so it won't hold a ton of heat.
If anyone disagrees with any of these numbers speak up....Our shop uses 1/16" and 3/32" diameter wire and it takes a bunch more heat to melt off those wires than this smaller .052"....