Just got through painting the engine bay of the 69 mach 1 (San Jose) and it looks great...probably to good,
Seeing your car was around the 17xxxx's I've included some examples from that period below
But didn't the firewall get sprayed with the sound deadener also? If so, was it complete coverage or?
Not sound deadener but an adhesive they used to seal all the openings. No it was not complete coverage, instead around or over every spot where there was an opening in the firewall was the plan except for the ground wire and screw which was added later.
Around (this time period and plant)
- heater wire, heater mounting bolts, heater hoses , any brake clip, throttle linkage, wire or electrical junction box, steering column, master cylinder or booster...you get the idea