A quick thing I would do is try turning the engine by hand (with the fan) both directions. If it is free one direction, but stops going the other something could possibly be broken. Like everyone said, poor something into the cylinder, and let it sit for a day or so, then try turning it over by hand, it is possible that the starter may be faulty. If you cant turn it by hand with the fan, you could try forcing it with a screwdriver, or something in the flywheel, but to a certain degree. You dont want to force it too much, you could make things worse.
Im sure people here are going to disagree, but from the looks of it, it may very well be froze up. I know on my 55 chevy, the 235 can be tuned over by hand with the fan very easily, but probably because the motor is so wore out and needs to be rebuilt.
Good luck with your project, its always fun exploring in the world of mechanics, especially on older vehicles.
- Shane
