Someone correct me if I got this wrong.
Yup, you got it wrong. My former '80 152 (built in Nov 1979) has the smaller N-number.
Mine is also a 1980 model built in 1979 and it came from the factory with 2" numbers.
When I had it painted 22 years later it didn't qualify as "Antique" so I had to put the 12" numbers down the sides.