P38 over pressure coolant Heather tank

Hi there after a bit of advice.

Took p38 4.6 to get LPG serviced all going well. All done vehicle cranking not starting then it happened, coolant starts posing out of Heather tank. So heads of later this week, question is new heads possible, however would you recommend changing radiator. Please help

To further my questions will a coolant flush help prevent this again once heads changed fixed