Another issue with including an ACI label is that they were only used for about 10 years, roughly through the 70s.
Cars painted before 1969(?) had them added later, so models of those as-painted shouldn't have them.
All cars through most of the 1970s were required to have them for interchange.
Many roads removed them after they were no longer required, so those cars that did have them in the 70s, as-built or repainted, on model railroads set in the 1980s or later, also wouldn't have them.
I model 1974, so all of my cars have them, but that puts me in the minority. If you want to add them, Highball Graphics makes some very nice ones in N and HO, for a lot less per-car than buying MicroScale data sets.
https://highballgraphics.com/index.php/results/no-category/aci-labels