I don't think the upper cowl area leaked on the drivers side. Same goes for the windshield. The upper cowl and windshield area are in perfect condition with no rust. The wiper pivots showed no signs of leaking either when I was disassembling the car. I think that rust was from winter.. A lot of cars rot here from getting in the car with snow covered boots and constantly having the carpet and underlay wet/damp rots the floors out in a hurry. I'm sure this car was driven in the winter at least half of its life.
The passenger side pan was rusty too, but that was a combination of the upper cowl seam sealer failing and a bad heater core.. And most likely damp carpet thru it's life from a passenger.