D&D 5E Monster Construction

[Lichemaster]

I want to use this monster in my Lizardmen den

http://www.coolstuffinc.com/p/125476

it is large size.

I will use the Ogre stats from the Monster Manual. Challenge 2 (450 x.p)
I then want to give it 2 abilities from the crocodile entree from the same book. the Croc is challenge 1/2 (100 x.p)
1.hold breath for 15 minutes
2.a bite attack that if it hits grapples (just like the croc entree)

What would you say this creature challenge rating is?
a 3? 4? would you allow it to have a bonus or atvantage as it has hands to grapple as well as the bite? do you have other suggestions of a creature that does something similar I can re-skin this as?

Thanks..........


just to be clear it only has 2 attacks and has to choose between them not 2 attacks.

 

[MonsterEnvy]

It's still a two.

 

[the Jester]

Unless you alter its AC, hit points, damage output or attack bonus, it will have the same CR as before.