will 03 impreza motor be a clean fit to 02 outback

Hmm.. if the wiring doesn't match up perfectly, you may still be able to swap short/long blocks and keep your intake and all the sensors, etc to put on the other engine. I just went to RockAuto and started looking at Fuel/Air parts and already found the MAP sensor is only 03 Impreza and 03-04 Outback. So that's one difference. There's too many variables for me to give a definite. It would be good for the forum if you keep in touch on what you find out. Look at / take pics / compare the engines and see what differences there are.

Both have the same 2.5-liter Four cylinder. I presume that were talking about two engines with the same transmission arrangements. I would think this would make things easier. I also imagine that the 2003 is in significantly better shape than the 2002 otherwise why do this. If it were me, I'd have my mechanic swap them over and shift responsibly to him. Remember, it's always better to have a single point of contact for anything that goes wrong. I know that you're trying to save money, but, time is money and getting it done right and professional. Just a thought, you'll have many miles of trouble free driving. How much could they charge if you hand them everything? Besides, they may have a few tricks up their sleeve. Good luck.

Yes, I see that your 2002 Outback threw a rod. How did that happen? Did that car have a manual transmission?