wont start

I have a 1998 3lt auto super custom series 2 with 161400km. At present it is not running and even after having several diesel mechanics look at it it has everyone stumped. It originally blew a hole in the head of the motor and since then we have replaced head and cam belt, yet it still wont start. The timing has been checked, it turns over but wont fire. Any one any suggestions before i decide to just post it in the for sale section as it is????

Could be the ECU ?

Sounds a bit like mine, Its been really hard to start since the new head was fitted. A good battery and engine start spray get it going eventually. Do the plugs stay on as long as they used to?