I believe that under 141, you must have 15 hours of dual instruction. You must have 35 total training hours. In the case of the IR, all training time is either simulated or actual instrument, or FTD/sim. So you could do 20 hours of safety pilot. In practice, most 141 schools do the entire 35 hours as dual instruction because it takes that much for students to be ready. Up to 40% can be done in an FTD. If you have access to one, that might be the place to start.