You can buy the shells but you will more than likely find its also put a lip on the crank which you cant get out to get reconditioned, from what I remember as it was about eight years ago they have a plate welded over the end of the crank to stop you dropping the crank out. Easiest option is a new engine.

Its a Common failure caused by running on wrong grade oil...needs 5/30 synthetic or you will blow the big ends...my brother did 2 engines in his old 1.4 zetec both went just after doing oil changes using the cheaper and thicker grade oils, wasn't till I spoke to a engine blue printer that worked at Ford Dunton and he told me it was because due to this reason, the thicker oil cant get back down to the bottom of the engine quick enough to stop oil starvation