Ok, so, I've removed all the pulleys using an air gun and without locking the flywheel since the engine won't rotate even with a huge wrench.
Took the engine apart and I need the opinion of the experts.
This is what I've found:
This is how the head looks. I'm not very familiar with rust/oxide on valves, but it doesn't look very nice to me:
As you can see cylinder #4 is the worst and I've also found an oil leak in the exhaust gasket:
Still issues on #4 by looking at this head gasket:
Pistons and block. They're completely DRY (as the gears inside the engine below the distributor) and stuck, even using a wrench they won't move. Cylinders surface looks good tho:
Water pump hole:
Distributor, not much left of the plastic ring:
Still have to remove the oil pan and the intake manifold, but judging by these images what do you think of the engine?
Is it shot? Is it worth reparing? If so, any suggestion on how to proceed is gladly appreciated!