That build is kind of bad.
First of all, you should ALWAYS spend your starting gold. You don't need to save 1000 gold to get Boots of Swiftness. You spend 350 gold on basic boots at the start...and then spend 650 gold on your first trip back to base. Basic boots are now Swiftness boots. You don't save money buying the whole item compared to buying the parts and upgrading.
Second of all, why are you getting Swiftness boots... You are going to get wrecked by CC (slows, stun, fears, snares). And CC wins games. On the off chance that no one on the other team has CC...then okay, maybe Swiftness boots but really...those boots are rarely a good choice.
Also, why are you rushing Tier 2 boots... Doesn't help you land your abilities. Doesn't help you survive.
Shurelya's Reverie is not needed on Cho'Gath. A catalyst and proper last hitting to active your passive should be all sustain that you need early-mid game. Plus, builds into more useful items. Like a Banshee's Veil or Rod of the Ages. Also, Shurelya's Reverie does not give cooldown to your teammates.
Never get snowball items like Leviathan. Worthless against competent players. Might work against bad players but almost everything works against bad players.
More importantly, you don't stack health on Cho'Gath. That's not how you build tanky. Straight health is worthless against Madred's Bloodrazor and percentage based attacks. Plus, there are far better tank items that give defensive stats and other useful effects. And Cho'Gath gets a lot of free health anyway. Why would you stack more health on top of that? Get some other defensive items. Like a Frozen Heart or something.
Trinity Force isn't a bad item...I wouldn't get it on Cho'Gath...but that's is because I rather build him tanky AP or CDR tank. All his abilities scale with AP.
Spirit Visage isn't bad...but your regen from last hitting isn't very useful as the game goes on anyway. 15% more of it is...okay...but I wouldn't dedicate a slot to it. I suppose the CDR isn't bad but I know I can get max CDR with Frozen Heart, Masteries, and a blue elixir (or at least pretty close to it). Don't see the benefits
Haunting Guise is straight useless. Go Abyssal Scepter instead.
If you really want to autoattack people as Cho'Gath, then I'd recommend a Wit's End. Also has good MR. Malady can also work...but...eh... don't see the point when Cho'Gath's biggest damage nuke is true damage anyway.
I want you to try a different opening. Open with basic boots + some pots (or Doran's Ring if you plan to be aggressive with your abilities). Work toward having just the basic boots and a Catalyst. If you last hit properly, your early game should pretty good in terms of always having a decent chunk of health and mana.