Welded combustion chambers?

I have used the Victor powder flow torch for cast iron in the past. It seemed like an excellent way to make closed chamber heads except for the exorbitantly expensive iron filler powder. Do you care to share what series of rod you use and if you you SMAW ac or dc (if dc straight or reverse polarity) , or dc GTAW your chambers up? Ever try flux core gasless wire welding? I am thinking of doing a set of 360 heads but don’t want any more scrap iron than I already have! I plan using a fire pit and hardwood and laying plate on coal, place head on top and allow to heat before welding. Cover with half of a steel drum when through to smother fire and let cool off gradually overnight.