Outer Limits 4x4 Board

Hi, im located in Melb. I think the head on petrol gas 4.5 cruiser is stuffed. Car has done 400k, loosing water and cuppachino under the oil cap.

1. Can someone recommend a good mechanic in Melbourne that can do the work at reasonable price. (prefer northern suburbs)

2. What should I expect to pay???

3. Is it worth fixing the head with 400k?.??? How tired would the rest of the engine be??

Thanks for your help........

A few mechanics recommended adding head sealing solution to the radiator with clean water, run and flush the system. Several have used it before with successful results. Internet searching also claim good results with the same product.
Still testing but might have fixed the problem for now. Maybe a band aid repair if it was a head gasket but at least I can still use the vehicle until I source a reliable repairer.