I overdosed on 3 out of 4 of those all at once a couple months back (trazodone, buspirone, and olanzipine) along with a few other meds. Ended up in the hospital 10 hours later so high that I cannot remember anything that happened that day, but according to my dad I had to get my stomach pumped. I was also had extreme trouble walking for the next couple of days, but that was the only lingering effect.
I've overdosed on blood pressure meds separately before, and all those really did was make me pass out a lot.
Basically, this combination probably won't kill you, and probably won't injure you, but risk of the latter is definitely higher than the former. Overdoses are unreliable in general, and I think the main way they kill you is through liver and kidney damage, so probably a bad choice for that too.