So, so far we have
Improved Critical (bite), Improved Initiative, Weapon Focus (bite), Great Fortitude, Iron Will, Lightning Reflexes, Epic Fortitude*, Epic Will*, Epic Reflexes*, Power Attack, Improved Bull Rush, Awesome Blow, Snatch, Superior Initiative*, Endurance, Epic Endurance*, Diehard, Flyby Attack, Hover, Wingover, Cleave, Great Cleave, Overwhelming Critical (bite)*, Improved Critical (claw), Improved Sunder, Improved Overrun
which I think is 26 of 34 including 6 epic feats.
You left out Dire Charge, one of the most important Epic Feats.
Awesome Blow seems a bit useless for it, since it'll be better off using Dire Charge, its Ramming attack, or Snatching an opponents and tossing them away.
I was going to propose Weapon Focus (claw) but I got Improved Critical (claw) listed twice for some reason instead.
However, Epic Prowess is a better pick - if we give them that feat twice instead of Weapon Focus (bite) and (claw) it'll get +2 to attack with both natural weapons instead of +1.
Overwhelming Critical doesn't seem that useful. Its critical hit bite already does 32d6+64 damage, making it 33d6+64 adds +1d6 only increases its average critical damage by 2%.
Fast Healing and Damage Reduction seem more useful.
Let's leave Overwhelming Critical in, at least for the time being.
Assuming we go for the Improved Multiattack option, that suggests:
Cleave, Damage Reduction (×3)*, Diehard, Dire Charge*, Endurance, Epic Endurance*, Epic Fortitude*, Epic Reflexes*, Epic Prowess (×3)*, Epic Will*, Fast Healing, Flyby Attack, Great Cleave, Great Fortitude, Hover, Improved Critical (bite), Improved Critical (claw), Improved Bull Rush, Improved Initiative, Improved Multiattack, Improved Overrun, Improved Sunder, Iron Will, Lightning Reflexes, Multiattack, Overwhelming Critical (bite)*, Power Attack, Snatch, Superior Initiative*, Wingover
The above is 34 feats, of which 14 are Epic.
I'd think swapping the Epic Prowess for another two Damage Reduction feats would make sense, giving it a meaty DR 15/—.
That still leaves it with +125 melee attacks, which ought to be enough for most opponents.
Feats: Cleave, Damage Reduction (×5), Diehard, Dire Charge, Endurance, Epic Endurance, Epic Fortitude, Epic Prowess, Epic Reflexes, Epic Will, Fast Healing, Flyby Attack, Great Cleave, Great Fortitude, Hover, Improved Critical (bite), Improved Critical (claw), Improved Bull Rush, Improved Initiative, Improved Multiattack, Improved Overrun, Improved Sunder, Iron Will, Lightning Reflexes, Multiattack, Overwhelming Critical (bite), Power Attack, Snatch, Superior Initiative, Wingover
We've also had Multiattack and Improved Multiattack suggested. Of course, this is one of those unclear issues. While it has 3 individual natural weapons (1 bite + 2 claws), it only has 2 listings on the full attack line (bite, 2 claws). I think in the past we've allowed this to meet the prereq for Multiattack, but I don't think I've seen an official ruling on it. Are we agreed to allow Multiattack?
We've had this issue raised before, and it doesn't seem unclear to me.
There are creatures with Multiattack in the SRD that have 3 attacks using two "listed" natural weapons, like the
Ghoul, which has Multiattack and a claw/claw/bite attack routine.