I'd say you have it exactly correct. According to this Wikipedia article, the NAPLEX has 185 questions, 35 of which are trial questions. Though you can't distinguish between trial/test questions and the real ones, they nevertheless do not count against your score.
This means that your final score is based off of how many questions you correctly answered out of 150 total; getting a 60% on the exam equates to answering 90 questions correctly.
Although, in the article, the author is careful to mention that this is a rough estimate and not the official number of questions needed to pass.
For more information, here are a few other Noodle resources pertaining to the NAPLEX exam.
Hopefully that answers your questions. Best of luck!