I see that the rust out is right at the dirt line on the door. I dug a Tudor just like this, out of a river bank about 45 years ago. There wasn't anything salvageable below the dirt line. It was a lot of work for nothing. I still had to pay WSP officer Terry Willard the finder's fee of a pair of 1930 Model A headlights. Live and learn.
I've seen a 36 coupe, with Ardun heads, that had been used for flood control, to protect the bank at the edge of an old barn from eroding away. The pictures of the rebuild were unbelievable. It is amazing what talent and money can do.
T-Model, Dog here, I betcha' a Dog bone thet thars a DAID body in thu FLOORBOARD I read sumwhere thet a guy wanted to be burried in his car, I BETCHA' THET'S HIM!!! Buster T.
In that yellow clay soil I would not attempt anything to save sheetmetal below the beltline as I have found in the past that once that type of soil holds alkalies that once washed off the metal quickly deteriates. The Sawzall is your friend in quickly salvaging what you see. Maybe dig off the soil down about 4 inches and cut it off there. Rod
Farmers used to put car bodies in washouts to help slow erosion. I have salvaged quite afew from these washouts. It is buried that deep from silting in over the last 50 years. Rod