Technical Stuck Motor - What to do next?

So, what are "we" solving for here on the Model A ?

 

Shades of Back To The Future..

 

If the pistons are stuck, the crank should move just a little bit back and forth. If the cam is stuck the crank should still move a little bit.

If that were mine I would loosen all the rod bolts, and maybe slacken the mains too, just a bit. I would see if the crank moves just a bit. if it does I would turn the crank lets say clockwise and work out which pistons it is moving away from. I would use a wooden slug and hammer on those pistons only. see if they want to move. I would then rotate the crank the other way and try the other pistons.

By doing it like this, with the rod bearings loosened off you are only trying to move one piston at a time instead of all 4. If one moves use the crank to push it back and keep moving the piston up and down. Only ever knock on a piston if it has a gap between the rod and crank. Hopefully you should be able to get them all moving eventually and slowly work your way to at least two full rotations of the crank. You want two full rotations to make sure all the valves are moving.

If the crank moves but stops before making two full revs then a valve is stuck.

Liberally dousing everything in penetrant is very important.

If you free it off it would be best to pull the pistons to make sure the rings are not stuck. They can be tricky to free up but it can be done if enough care is taken.

The engine looks to be in pretty good shape from the pictures shown and ought to free up quite easily (fingers crossed).

Mart.