Dont give up I am sure I have a solution for you blowing your head. I am a big mercedes diesel fan and have followed this guy who is putting out alot of ponies from a 5 banger.
Here is the link.
Mb 2.5d 20v superturbo projekt - Page 2 - MBWorld.org Forums
I sure since he used this he has not blown a head gasket. Here is a picture of the bottle.
before he used the spray he went threw MANY head gaskets