Is there a reverb that can give me live reverse reverb? (Yes with a massive buffer is fine)

I'm in ableton, and I have this song where the tempo changes like 3 times, and I'm trying to apply a reverse reverb to the vocal (Typically I would freeze, flatten, reverse, apply reverb, freeze, flatten, re-reverse, and blam I'm done. But with this particular song these tempo changes make it impossible because none of the timing lands properly after reversing, etc. I was wondering if there were a way to do this "live" so to speak, with a MASSIVE buffer size. Are there any reverbs that do this?