For me BPM was 79,6 something. Try putting the vocal it on a 80bpm or 79,6 (if you like) hiphop beat; it’s OK. Worked w me at least. Since vocal is not fm machine, you could cut here and there, push a little bit, stretch BUT in ms (millisecond) intervals.
LMK what happens.

Fruity loop detected it at 79.595 BPM or something like that but as you said a voice is not as regular as a beat and it seems to be unsynched… Maybe it’s me and my ears ;)

I finaly get the right BPM (it works for me), I download the original track on Eddie Bingo’s myspace (btw listen to that track if you can it’s a real good one), I work that track as a sample and find the BPM, it’s 92bpm.
Hope it will be usefull.