Fast Guy
Give a quick check to those dissimiliar metals.
I've never seen 5356 sheet..... As far as I know 5356 is a singular designation for wire
Also when you have determined for sure your two alloys to be joined let us know about service conditions... Hot, Cold, Need strength max, need ductility max?? etc.
Also also, let us know if you are going to annodize and if color match between filler and base metal are important...
After we know all that stuff... You will get solid suggestions