Cummins C6 8.3 head gasket?

Hi all, I'm thinking of buying a 97 Acco 2350G with the standard Cummins C6 8.3 under the cab. It appears to have a blown head gasket and is pressurizing the cooling system and blowing a few bubbles when the overflow hose is put in water.
Could this just be a blown gasket or something more sinister?? The engine was overhauled back in 2012 and there is no evidence of overheating.
Any info would be appreciated, Thanks.

i noticed that truck for sale as well i was a bit sus about it ,at the end of the day its a unknown quantity could be just a gasket could be a lot worse .. my acco has the same motor & has been problem free ... since the engine was overhauled back in 2012 ask how many kms it has done since if hardly any that could be your problem a rebuilt engine that was still "playing up"

Hey mate, I think that the head bolts are a torque to yield bolt, so if it was a bit of a cheap rebuild, they may have not fitted new bolts. I've seen it happen before....