Don't think the chain would need to be cut...tie-wrap or wire the chain upward so it does not fall down into the front of the engine causing a jam. Unbolt the cam gear, move it forward off the camshaft and take the head off. Take pictures first!!!

Is the engine on a stand that can be rotated? If the oil pan can be removed it may be easier to determine what is stuck and to soak the bottom of the pistons and the wrist pins.

Good luck and keep us posted!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer