I dont know where all my pictures are of this repairs I will try to locate them.
But basically whole Cowel had to be removed, I used a set of A pillars removed from a Parts car which I used the Skins off of for the pillar post.
I cut all the rust out and Shaped new pieces from Fresh sheet metal sheet Steel and Tig welded it And Mig welded it all back together.
I wouldn't dream of trying this repair with just a Mig only though! Don't get me wrong a Mig has its place but welding Thin sheet metal isn't one of them in my opinion. Better off using Gas in a Lot of cases especially on Skins.
This is NOT a Repair to be taken lightly! or Half assed together!!!!!!! A lot of forces are exerted into this area in an accident whether hit head Broad sided from a side impact or a Roll over.
Take your time do it right! Some ones Life may depend on your work!.
The Skin under the Cowl in the corners is a Thicker metal where it ties into upper rocker panel and supports the Cowel panel & metal for the fire wall and in the Piller under the skin is heavier too as I remember.
It is possible to get new whole upper and lower Rocker panels to Cut these pieces from. I looked into buying it new But they are whole parts and expensive just to cut up for patches, I also looked for a Complete parts car to cut them from. But available one in my area guys were trying to sell as re builders rather than parts cars so I opted to metal shape my own from the correct thickness metal. A whole rust free parts car would be the way to go IF you can drill spot welds really good, Also I Glass blasted all my metal free from all rust.
Right side after repair left same
Again i will try to see if the Pics are on my garage camera and will up date my 70 thread with them.
This is a doable repair But remember its a Major Structural part it has to be done right.