Hey there! This is a guide to mostly diver Cho'Gath. If you find enemy carries tasty,too, let me introduce myself: I am Matt- Feasting Carries since 2016.

[TOP]: Grasp is the best option- it gives you permanent health, sustain and more damage- try to proc it as often as you can! I prefer Conditioning over anything else.
[JNG]: Dive Cho is taking Predator. If you need to play a more peeling role,you can take Guardian .
[MID]:You have to play like an assassin- so build like one!

Unless you play safe and totally together with your team, I don't recommend getting a Warmog- although it has valuable stats, for that price you can get another resistance item.
Gargoyle stoneplate double your bonus and base health, but doesn't cut down your ultimate's damage: at level 16 your ult will deal 650(base dmg)+[270(runes)+400(R.Glory)+400(Randuin/Dead Man's)+350(MR item)+160*(6+feasts stacks from minions)]*1/5 true damage to your enemy. This equals to a mininal damage of 1100- but I'm sure you'll have some stacks from enemies as well, thus further increasing the ultimate's damage.
Spirit Visage isn't a great items on Cho'Gath becaus of the simple fact that he doesn't utilize its passive of increasing incoming healing very well.

My jungle path:
Red-birds-scuttlecrab, look for a gank/invade or go wolves-blue-gromp-other scuttlecrab.