The affect on delays allow you to continue if you originally planned the Part 135 within the 14 hours (providing you with the required REST). Tbe discussion is can you plan to end the Part 135 within the 14 hours, then continue Part 91?
Kidd (2012) doesn't provide that answer.
Slater (2015), however, does provide that answer. The answer being YES you can operate Part 91 which has no 24 hour look-back REST requirement.