Engine out, going to strip engine and hopefully if it doesn't need a rebore or new head will rebuld with new rings, shells and bearings.
Yes that is body filler, this part of the chassis on both sides of the van was made up body filler, cardboard, chicken wire and coated in underseal. Has now been replaced with steel.
The other side isn't any better.
Replacing both wings
After the rot has been cut out.