Just wondering if there are any members Perth based who are mechanics. My diesel Courier ute has just done the head gasket, damaged the head and valves. I have been quoted a huge $4000, but it must be able to be done cheaper!
try to souce a reconditioned replacement head, complete with everything you need, check the deck for warping or cracks with a straight edge and feeler gauges. chuck a new head gasket in there and away you go....its tricky, but if you half mechanically minded you can nut it out...buy a workshop manual, it will guide you through the process and let you know the finer details of head bolt torque specs and timing alignment...
if your not technically minded, go to your local tafe and ask if the students would like a project, sometimes they love to get these type of things in there to teach students real world applications.
maybe you could buy a complete long motor and replace the entire engine, or find one with bottom end damage and swap the heads.
Diesel engines rely on compression for ignition, so a leak will be terminal for the engine performance
did the engine snap a timing chain? if its just popped a gasket i suspect that you may not have done valve train damage.