4jg2 radiator over flow tank etc

[thewizard]

Hey guys
So a few months back the wizard i purchased had a diesel runaway due to turbo pissing itself . Since then i had turbo replaced brand new and all hoses and what not .Wizard is working fine-ish. I have flushed cooling system replaced thermo with brand new one ( currently running water atm) No overheating at all. I believe the water in radiator is not circulating properly and i can hear air coming out of the radiator cap aswell , also over flow tank is boiling/bubbling . Possible head crack or gasket

[thewizard]

Any suggestions to look into apart from head/gasket . Does run rough when cold started once warm the truck just turns over as normal , also looking at getting water pump with radiator cap.