You are absolutely right there on those numbers, no need to change them. However... looking at your mana curve you've got an enormous amount of 6-drops. Your average mana cost is over 4! That's some battlecruiser magic - very vulnerable to board wipes, mind you. You'll have a bad time if someone starts removing your creatures.
I think you need to do your cuts higher on the curve because you should have a clear board presence by the time you cast Xenagod. Six drops aren't going to cut that. I would personally cut the entire "one shot fatties" category except for a few creatures:
Primordial Hydra,
Savageborn Hydra,
Embercleave and maybe
Hydra Omnivore. Instead, you need smaller things like
Predator Ooze,
Managorger Hydra. You could toy around scaling threats like
Mistcutter Hydra or other X-costed creatures. I'm also not sure if you're going for Dragons, Hydras or +1/+1 counters.
You've got the right idea but I think you're aiming for too late game and you'll suffer some casualties on the way there.
EDIT: If you want you can take a look at my Hydra-themed deck here:
https://deckstats.net/decks/93006/811329-rosheen-meanderer-x-fatties-50/enIt has a distinct X-costed theme and the finishers like
Overwhelming Stampede or
Triumph of the Hordes are at the very top of the curve between CMC 5 and 7. I have the advantage of being able to pump an additional four mana into my spells but the basic idea is pretty much the same as yours: lots of fat creatures,
threaten the entire board with them.