I say keep the GST, save up money and down the road grab a 240 on the side. That's what I would do. I don't see a point in trading a car that you worked hard on for a car that you don't know much about. If it was a close friend of yours and you knew about the car inside and out then maybe, but...
Check to make sure all the bolts are out, make sure it's in neutral, and if you need to try to twist it a little and tap it softly with a rubber mallet to try to losing it up.
The motors are the same, the only difference is 6 bolt and 7 bolt. You just need to get a AWD transmission, t case, drive shaft and rear end if it's not already on the car if you plan on keeping it AWD.
Amazing how people come in here and throw turbo cars around when the thread isn't even about turbo car advise or comments. I believe the question was asked about a Eclipse RS NOT GST, GSX, or TSI...Seriously people learn to read!!