Do you have the assembly instruction manual (A(M)? The AIM shows how the floor pans were riveted and bonded to the cowl, down to, and including, how much bonding agent/sealer was to be applied to the joint.
If you are not getting weather in the car, you're probably okay leaving the unbonded areas as they are. What you see inside the car is only one side of the joint. Check the joint from under the car.