In my opinion, the best NASCAR kit ever is the 1989-1992 Lumina from Monogram (Revell). They updated the chassis to modern standards and this was before most of the Revellogram kits started shipping with badly warped bodies ('94 - '97 Thunderbirds, especially).
Second to the Lumina, IMO, would be the early '80s Buick/Pontiac/Chevy kits. Very well done and they build up nicely.
For AMT, I feel the Lumina body looks the part quite well, while they missed the mark on the Thunderbird and Oldsmobile. The chassis are great for updating other kits though.