Yeah, I was thinking that it would be beneficial to make the "first pass" with the tig welder and then fill any big holes with the miggy from there.
Like if there's a quarter sized hole in one case half, make the first round with the tig welder to "break up" the first layer and get good aluminum down and then add on more and more material to fill the hole with the mig welder and spool gun. I think it would speed up filling operations versus sitting there plodding along with the tig welder one dab at a time. Plus, I'm the biggest kid ever and LOVE to play with new toys. I:I
To the OP, you can give the alumiweld brazing rod a shot. I've used it before with mediocre results (some positive, some not so much) but in my opinion, the problem you have is beyond the scope of what the alumiweld can handle.