Anyone know this car/owner?

Perhaps he blocked off the cowl air vents under the dash? With the vents intact, fumes would definitely be a problem (as you already pointed out).

He might be okay if he never uses his heater or fresh air vents but mine was a daily driver. Don't remember how long I put up with it but I know I disconnected it. I did put up wit a lot of other stuff around that time though. Gears, solid lifters, no choke, open scoop, lousy heater, super stiff clutch pedal, poor gas mileage, fenderwell headers..... Fun times! :thumblef: