08 engine locked up ? Replacement ?

My daughters' BF bought an 08 Cobalt at a car auction on Thursday. (as is, where is..). He picked it up on Friday and drove it home. It had a loud ticking noise on top. I pulled the valve cover and saw that the rockers on #1 exhaust were loose. Not sloppy, but enough to move around. All the others were tight (even after cranking to different cam positions). He wanted to take to work that day (about 5 miles one way on city streets), and on the way home it just quit running. Pulled over, put in park, and hit key. Sounded like about half a turn, and then nothing. Just clicks after that. Someone stopped to help, and thinking electrical, tried to jump start it. Still nothing. Our quasi-mechanic neighbor thinks the engine is seized. I've tried to wire around the ignition by running power directly to the starter to see if it would engage. Put it to the large terminal, and the starter spins, but does not engage. Put power to the plug in side, and it engages, but does not spin. To me, that says the starter works and the solenoid works; but the engine won't turn because it's locked up. I want to try and move the harmonic balancer to see if it will turn, but I don't see any way to access it. So first part of question is: any suggestions to further the diagnosis ?

Assuming the worst, I found a relatively cheap ($100) engine from an 05 Saturn Ion that has a blown head gasket. Any used engine I would get, I would put rings and bearings in anyway, so this seems like a good way to go. I see there are several versions of the 2.2 Ecotec, and a lot of the random parts I compared on Rockauto show compatability between the two engines. What should I be looking out for in finding a match ? (I'm mostly an old front engine, V8 kind of guy -- never messed with fwd much). Appreciate any and all suggestions.

I like to use http://www.car-part.com to look things like this up.
Their search feature should give you good idea of what parts will part interchange with your vehicle.

End of story for future reference: Pulled the right front wheel, and removed splash shields and got access to the harmonic balancer. With a breaker bar and long extension, tried turning clockwise, but nothing. Then moved it about 180* counterclockwise. Tried clockwise again, and it stopped at the same point. Turned back the other way and turned further and it went 360*. Turned it back to the right, and it went past the point that it had stopped previously, but a friend listening near the motor said he could hear a grinding noise. Tried the starter again and the engine turned over and actually ran (sort of) but spewed out a lot of smoke. Let it sit for a day and drained some oil from the pan. I found several chunks of metal about 1/8" by 1/4". To me, they looked like part of the piston between rings. He said screw it, and sold the car.