depends what engine you want in it. if you just want the same 1800 or even the 2litre its so simple.
just mark every plug in the engine wire loom so you know exactly where to plug them back in the new block, if you have an engine hoist use it to support the engine (or just use a couple of jacks under it) then loosen all the bolts from the engine mounts, take the bolts out and jack the car right up and lowert the jacks under the engine and let it drop out.
fitting the new engine (i would go for the 2 litre) you will need an engine hoist to make it a lot easier. just position it in place and the mounts should line up perfectly if the donor engine is from a mondeo, then just tighten in all the bolts and plug the loom back in (remember all the plugs will be marked)
remember if you split the new engine (take the top end off) you should put a new head gasket in and new head bolts as they are stretcher bolts and can only be used once also they need to be torqed in the correct sequence and correct torqe.
if you want the st24 engine in it then its a bit more tricky!!!
good luck mate, if you get stuck or have any more questions e-mail me rossthedon@hotmail.com
Ross
October 2005