I am not a very good welder, but have been forced to learn metal shaping so I can make patch panels…(especially for a corner behind the wheels etc), as no patch panels are available for 420G…they may well be for MK2 ?
is that accident damage…or a couple of pieces roughly brazed in to cover rust ?
I have a similar repair coming up, same corner…10yrs ago I brazed in a section, as it was too hard and time consuming for my skills at that time.
I will need to remove the door, reconstruct the lower A-pillar, and area that is rusted on yours by forming new inner and outer lips.
One thing I have learned is to make a patterns out of thin aluminium (throw away baking dishes)
This means I have an accurate mold to check for shape…I do this before I strip the bondo
I also have to make separate pieces and weld them together, lacking advanced metal shaping tools
a contour gauge will help a lot to
take off that front wheel and check directly behind the tyre where the toeboard panel joins the inner guard and floor