This is the list I have that got my 2.5/2.2 swap running in my 2001 OBW
2.5 block
2.2 heads (dual exhaust ports)
Custom intake manifold adapters to mount the 2.5 manifold on the 2.2 heads ($140 at my local machine shop plus some tig welding at home)
Depending on your trans/ecu your cams and crank gears will need to be swapped out. there is a huge difference between the two sets
2.2 timing tensioner and belt