Seam sealers located on the A pillars and in the engine bay on a late (June) 70 built San Jose Mustang would have been applied as follows
On the cowl to firewall, A pillar seams and cowl to side cowl panels - these were applied before body color. as shown below
Black baked off cowl top
A pillar seam - not done on early cars but done on later examples
Sealers on all (well that was the plan) of screws, master cylinder to booster to firewall, hoses and electrical pass-through items would have been applied after the black engine compartment paint
Front wheel wells - sealer under black paint. Sound deadener over black paint (after car is assembled)
Hope this helps