Pull the heads yourself and look it over, any damage should be fairly apparent. If you have questions just ask, many here can guide you through the process start to finish regardless of what you find and do to correct the problem. Repair that motor or replace it.

Taking it apart, keep track of all parts and their exact location.

Like the valve train, all parts removed should be kept in order and returned to the same location during reassembly. Each rocker arm and push rod goes back where it was when you removed it even though they are the same. Includes the lifters if you end up having to remove them, doubt it but same applies to them.

Make up a simple tray, small sheet of ply, egg carton what have ya remove each bank moving the parts to the tray in the order front to back as removed so you know where they where. Mark the tray "Front" so if you move it from place to place during the engine work, always do, you do not loose its orientation to the block.

You might not reuse the parts, but then again you might so don't just throw them all in a bucket.

Not all parts matter in that regard but if in doubt, you're just not sure and no one handy to ask, keep track of em.

As a general rule parts that ride/wear on one another need to go back where they where originally for best results. Saves em seating into each other again, previous wear patterns made by previous parts create excessive wear doing so.

Shouldn't take you much more then couple hours to pull the heads, little more for time for the learning curve if you never done so before.

Gotta digital camera, take pictures right from the start, linkages wire harness connections, bracket locations etc etc as you work.