Heal isn't the greatest spell to choose on any champion, but here it's even worse because the already-small heal will be almost unnoticeable with your massive health pool.

In addition, you're not taking into account that health is only as effective as the armor and magic resist you have to back it up. With 145 armor and 122 magic resist when you pop your ult, you're not tanky at all - just a little bulky, but nothing too hard for any decent carry to take out.

You're also not running dodge seals on Jax.

Attack speed marks and Sword of the Divine seem like a waste, since your ultimate already boosts your attack speed to high levels. Stark's Fervor will be more than enough.