Cowl Damage Detection

I am hoping to pick up a 65/66 at an event in June.  I don't want to be doing any rusted panel repair in the car I purchase.  I can see rust in most areas, so the biggest problem seems to be if the car has serious rust in the cowl area.  But, how can I determine if rust exists in the cowl?  I know if there is rust, water will leak inside and rust out the floor pan, but what if someone did a floor pan repair and replaced the carpeting?  I definitely don't want to buy a car that requires the very expensive rusty cowl repair.  Is there any way of telling if the cowl is rusted, without tearing apart the inside and looking up under the dash?     Does a rusted floor pan usually mean a rusted cowl?  

No not always, sometimes a rusted heater core can leak inside the car soaking the carpet and floorboards. If you are flexible you can lay on your back look up into the back behind the dash, use a flashlight you will see the bottom of the cowl should give you a idea. if it's dark out you can take a flashlight shine it through the cowl and look inside to see any light coming in.  

These cars all rusted, some more then others. Take a hose and run it down the cowl,,let it run for a few minutes on either side and then see if the floor is wet.  

I guess laying on your back with a flashlight is the final check before purchase, if everything else looks good.     I am hoping to buy at the Carlisle Ford Nationals, so don't think there will be an oppurtunity for the hose check, but my sister lives in Carlisle, and I will be requiring the seller to "deliver" it to her house, so requiring a successful "hose check" might be a good condition of sale.    

easy, take one bucket of water and pour it into the cowel vent and see what happens, it should just come out inside the front fenders...not inside the car..  

I have a 1969 Mach 1 and the cowl was very rusted. Didn't know to look when I bought it. Found out in rain storm returning from show. You will have to lay on your back and shine a light up under the dash board. You will see the rust. My pony is being restored and the old rusted cowl had to be removed and a new one welded in. It is worth finding out before paying the price.