There ya go....These guys know your engine very well so you can trust the advice here...
In answer to your question,I was looking at your first pic,the dark scorched looking area at the top from the cyliner to the coolant jacket.That looks like theres been excess heat build up and maybe a leak,plus as hydra mentiioned the white ash on the piston is a tell tale,coolant in the cylinder,tells me you may have had an overheat.
In my shop the heads would go to our machine shop along with the block.Full service on the heads and the block checked(I think they magnaflux there?) You have metal in your engine,all you SEE is in that area,it was pumped through your engine,as he mentioned,if you just go with head service and timing chain/guide kits prey,your investing in a engine that has metal throughout....I have seen worse though,

 

The FSm is in the DIY section,along with a parts manifest.Have a look at the timing chain and head components.When I get back later I can check and put a link for timing chain and tensiners up,if you haven't found it or someone hasn't done it by then...bbl

 

I think you can undue the nut, remove the gear and your replacement part should be one of these. Take you vin number with you to the dealer, I would sugest it would be the 53021393AA part number, but only a dealer can tell you for sure.

53021169AA With [NZC]

53021393AA without [NZC]