Personally, I would only consider solder or braze. The original picture from Otto looked like it was brazed, yours looks more like solder. I would trust my brazing since I have been burning things for 60+ years and have experience with dissimilar metals. Silver solder would be a good choice also. Find a welding shop or radiator shop, ask what they can do.

1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy