1965 Dodge Dart, Rain leaking in to the coupe

Hi folks.

I discovered rain coming into the car today. Dripping under the dash, so I have been out with the water hose now, and when I flush water into the louvres between the hood and windshield, it comes water into the coupe.

You know the two black doors on outer left and outer right side above the feet when sitting in the seat. The water comes down there and fills up and drain out on the floor in the car.
And it is significant.
I have not done anything with this yet, the car is so wet inside that I have just put a heater fan in there to try to dry it up.

What can be wrong ? The seals gone bad, or is something rusted so bad that it has to be welded, and how on earth do I get to it ?

Bill