any Falcon/Comet owners here know that Ford didn't waste a dime rustproofing these cars.... especially the cowl. the heater/fresh air intake plenum is a built in rust-trap and is the major cause of floor rustout in these cars. i've just completed the repair of this area on my '62 Falcon. here's some pics; your results may vary. the front sheetmetal has to come off; the engine can stay in the car. the windshield has to come out also, and you need to drop the heater, driver's side air box, and glove compartment. i used a cheap HF spotweld cutter; i recommend drilling a small pilot hole in each spot weld anyway. a wide, flat chisel is still necessary to peel the cowl top off. be careful not to drill all the way though both pieces of metal with the cutter like i did several times....
note if you can read it the measurements on each side of the cowl; that's the locating info for the cowl hats. they are DIFFERENT side to side; and while the driver's side is basically just an air vent (which is why i left that side closed), the pass side indexes the heater intake tube. not critical per se, but ya wanna be close as possible. looking at the "before" shots and the sheer amount of missing metal, it's no wonder that my floors were dissolving. if i'd had carpet in there, WOW. i'll have to cut back along the sides of the cowl top to remove some cancer and make a flange to weld down to the side panels each side. some owners close off the cowl air intake when they do this repair and rely on the openings on each side to supply air. that'll work too.
Thank you for posting this! I have one question. How did you remove the driver's side fresh air box? Were you able to do this without busting it? My cowl is in good condition, maybe I should just leave it attached. Doing a complete teardown restoration. This car has been in the family since new.
On my sons Falcon,we used an available intake repair kit! I have seen them A LOT worse that yours though.Most is caused by a build up of leaves,and assorted junk that holds moisture in the plenum.I use a long bendable nossle and blow the crud out,there should be large openings on each side and a drain opening on each side! ROY.