I received a reply to my thread on the Outback.org forum that I believe covers the main points, so I will post it here for posterity and so that any future "swapper" has more information for reference. It was from Subaru Expert - "grossgary". Here is his reply:
welcome, i travel to Canton frequently and through Columbus a few times a year. 1. ignore OBDi/OBDii stuff, that's completely meaningless for 1995 engines. 2. you have the right engine, 1995 EJ22 will bolt right up. with the EGR caveat: A. if it's an automatic it will have EGR like your EJ25 and you're done, install it. B. if it's a manual transmission then it won't have EGR. it will still run and drive fine, but if you can't have a check engine light then you'll need to get one with EGR. ***I doubt you'll want to do this but i would like to deliver some voodoo for eagleeye - if you wanted THAT engine from THAT supplier you could still use it by installing that engine and then getting any 1995-1998 EJ22 intake manifold WITH EGR. the intake will have EGR and you can then bypass the check engine light issues with some simple vacuum line plumbing even though your 1995 engine doesn't have EGR. unfortunately that little trick is impossible, or simply is not going to be done, on an intake manifold that doesn't have EGR set up on it. so the intake manifold is the driving characteristic. With an EJ22 EGR intake manifold you can use any EJ22 (EGR or not) and even EJ18's. Car-Part.com--Used Auto Parts Market *** You use the EJ25 flexplate on the EJ22 - but that's almost always kept with the vehicle so the mechanic would probably swap that anyway. *** slap a $100 Gates timing belt kit on there from rockauto or amazon. new belt and pulleys. Your EJ25 and this new EJ22 engine share the exact same oil pump, water pump, and all the timing pulleys - the tensioners are even interchangeable if you swap the bracket behind them. In the event that any of that is new on your EJ25, which seems unlikely since it seems the belt broke. Use a SUbaru water pump gasket, the cheap cardboard aftermarket ones suck.