Definitely, the number of games would stay the same. And I'm inclined to say that what you've done in is correct.
But I'm suggesting that since the distribution of opponents is not even, it may not be possible for the top 8 teams in each conference to finish with the same record. I'm trying to think if there is some caveat lurking (combination vs permutation which I always sucked at).
Considering
- 4 games against the other 4 division opponents, [4x4=16 games]
- 4 games against 6 (out-of-division) conference opponents, [4x6=24 games]
- 3 games against the remaining 4 conference teams, [3x4=12 games]
- 2 games against teams in the opposing conference. [2x15=30 games]