2nd hand lumps can come up for about 150-200 at the lowest ive seen mate, but obviously probly about the same mileage as what uve already got

and yeah a 2.0 will go in with a few mods to mounts etc.

but then again if the engine aint smoking etc and is in good nick, then they will run fro miles yet

head gasket aint a hard job (well no harder than any other) but there is one basteward bolt on the inlet manifold that takes some time to do