an engine needed, but which one?

[murdoch]

i have now saved up some pennies and i am after fitting a different engine into my dead 2.0ltr c.u. Aircooled camper.
i would prefer a turbo diesel, but i haven't ruled anything out
I've thought about staying Aircooled and selling the van, and buying a diesel one, but having owned it for so long i've become rather attached to it... any way i'm half way through an interior re-fit, and body job, so i think its worth it!
can any one let me know the best way to go about it, i.e. buy a whole running car ( if so which one?) or can any one sell / supply me with an engine and neccesary bits to do such a job?
any replies of help would be most welcome
cheers