Ouch! Did the friend blow an antifreeze line or did a headgasket start to leak? If the oil level was OK, then the block should also be OK.

Removing the head is not like the red blocks, this is a real mess with the overhead cams and glue. Removal is fairly easy, just remember to tag everything! Head bolts probably shouldn't be reused, and they are not cheap. And refurbishing the head is cheaper than getting an unknown engine.

You will not only get a new timing belt, rollers, etc, but also have an opportunity to replace the oil separator and its piping. Something to do while the head is in the machine shop.

Really, find out exactly why it overheated and how long he drove it in that condition. It will make a big difference in what you need to do to get it running again.

Klaus

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Always willing to listen, just not able to take direction.