How much work would be involved if I wanted to put a Mk3 1.8/2.0 Astra Sport engine into my Mk3 Astra, to replace the 1.4 that's currently sitting in there.

I've got the urge for a few more horses under the hood cos I'm doin quite a bit of motorway driving lately.

Also, where's the best place to look for a good condition engine.