..........So I have san jose built 69 mach 1 build date is 12/19 68. I know the bottom of the floors and rear of car were batch gray in color. The front of the car had been sandblasted by previous owner. My question is should this have same batch gray as I did rear of car or would it be red oxide?
Red oxide applied to the bottom of the front frame rail approx directly below (maybe a few inches rearward) from the face of the firewall going forward. Applied after (overlapping) the batch/floor color.
also what about backside of rear valance gray or red oxide?
The back side
Valance was attached (hung) after the gray was applied over the red oxide to the exterior of the body. Now the painter didn't always get a good coat of gray below the taillight panel area
The back side of the valance would IMHO not have received a direct application of the gray surfacing primer directly.
Not sure what model your restoring but the sound deadener blobs/smears appear to have been applied before the gray and certainly before it was attached to the car.
You'll normally get direct spray at the outer ends (the ends) overspray and a misting further in from the end, through the back up light holes and through the gas tank opening from the body color application