Interchangable Parts: i to an ix

[DarkWing6]

My brother has a 91 4 door 325i AT with 108k on it that was t-boned and might or might not be totalled. He can get an 88 325ix 5 speed for 2500 that has 250k on it. He was wondering if there are enough interchangable parts in it to buy the ix and basically put his engine in it and part out the rest. So my question is how much of the stuff on an ix is interchangable with an i?

[nando]

the engine block, transmission/driveshaft, front suspension (all of it!), steering rack, rear hubs/rotors are the parts that are not interchangeable. everything else is though. :P