engine rebuild questions

[blinkyeatu]

im buying a bosch pump with an older xud (D8a) engine attached, i was thinking of doing and engine clean/rebuild then putting it in my car its on 140k.
what should i do? 
what shouldn't i bother with?
what bits should i replace/upgrade etc?
anything i can do for performance with out spending crazy money?
anything else i should do whilest its out of the car turbos, manifolds?

[Dave]

Potentially worth putting in some HDi conrods, as these are noticably larger at the usual fail spot.
I wouldnt bother tearing the engine apart just to replace with same parts without upgrading.
If the block is out then maybe worth upgrading to a multi layer steel head gasket as these will be better than the fibre gasket the block will more likely have. If its MLS then leave it.

Leave turbo and everything else as is, it'll be good on a mild tune 20psi or so and it'll last.