sorry if posted in wrong section but in a bit of a rush =) looking at car on ebay with an hour to go

father-in-laws vec b 2.0 sri (140bhp) has had its day and he has spent alot of money on it so is looking to get another vec b in good condition and strip the knackered 1 down and keep the good bits.. he is looking at a 1.8 sri (120bhp) my question is are all parts interchangeble engine wise and exhaust or does he need to stick with a 2.0 (140bhp)