Pretty disusting spot.. I think it's safe to say that he is never gonna have worse than a straight for value, because sets is going to be checkraised extremly frequently this deep, dont think many player have any slowplays here.
So, he is unknown to me. Making a quick x/c otf and ott and snap x/jamming river. I think most people are more likely to tank before they bluffjam something like TQ,T8.
Not sure, this is high up in range, but my valuerange is also supernarrow in this spot. I would, and think its right to checkback all 1pair hands on this river especially this deep. So my river betting range will look like JJ,99, QK, 78s and maybe some TJs and bluffs