|Looking at my collection of pictures I can offer the following
1- Under the car - nothing before paint and of course no sound deadener was applied to the floor area
2- Front wheel well before sound deadener for your plant and time period, appears to be at the inner fender seam to outside frame rail. Up the inner fender to firewall/ wheel well section and down to the frame seam as shown in the pictures -= arrows. Sound deadener was not applied to the car was completed (fenders on, splash shields in place ......) minus the front wheels and tires
3- Rear wheel wells. No seam sealer except for a couple of piles of chalking where the inner and outer wheel house come together at the lower ends front and rear. Then sound deadener (with overspray onto the frame and floor outside of the frame. Don't know (have nothing in pictures) if Dearborn ran a ribbon around the outer wheel housing just inside the lip like other plants.
All of the chalking was applied by gun that smeared, wiped or smoothed with a rag dipped in thinner. I use a 1/2" brush with all but 1/4" of the bristles cut off dipped in thinner.
Glad you asked since the assembly manual does a poor job IMHO of where they applied sealers, paints, sound deadener when compared what the workers really did
Remember when looking at pictures here and elsewhere stay focused on 65 Dearborn only and from your cars build period