Perhaps Ben can help us here. I looked at both models in Mactracker and found no difference except CPU speed. How ever this doesn't necessarily indicate compatibility for a swap. Why would you want to do this? Is there a problem with the newer unit? If that's the case you may want to remove the board from the donor unit and hold it near the other unit. What you would be looking for is do the cables match--are the connections the same--do the ports line up in the case? If everything checks out and you feel froggy go for it. To be on the safe side I would either wait for Bens answer or email him at ifixit for an answer. Ralph
It's just not feasible to change your logic board. If you look at the cost alone, it's worth buying a whole new computer, with everything updated.
If you get past the cost, the work should be enough, unless you're a very experienced and talented technician with a lot of time on your hands it isn't a feasible repair.