[DannoXYZ]

Personally I would use this process for fastest, least effort (re-uses original bracket):

1. cut 1/16" steel circle 1.5cm diameter and braze it around hole to seal tank

2. make legs for fairing bracket from 1/16" steel, 1x4cm. Braze along top & bottom sides of bracket 1st so it's U-shaped. Then line up on tank and trim legs as necessary to position (measure other side as guide)*. Braze to tank when position finalised.

3. fill gap between bracket and tank will body-filler and shape as necessary.


* I think I would cut cardboard and lay horizontally next to tank and intersect bracket hole on good side as template. Trim so it fits flush with outline of tank & bracket. Then flip over to other side to use as guide for positioning repaired bracket.