Now I am again doubting.. I however saw a lot of cars having had this media/soda blasting and they were done right with no deformation or wavy metal.. I will think about it again, thanks a lot for your feedbacks!
Small update for tonight
As a lot of these old VWs, my ghia had in the past several holes made through the panel between tank and dash. They also did "update" the wiring loom by cutting some space for a big fuse box :cry:
So I made a patch panel:
And welded it and all the other holes:
And with rust protection primer:
(Of course as you may notice the patch was not yet welded on this picture..)
Antoine