04 aveo head swap... (donor is 08)

Ok, car landed in my shop with parts included (ugg) customer didn't tell me the head was off an 08.. Head has been milled and had a valve job so we're in to it for some $$ at this point. Interchange shows 04-05 only. But I did find a thread where someone used an 05 head on a newer block.

I can tell you the 08 head on a 04 block with a 04 head gasket WILL NOT WORK! well it will, but you have a minor oil leak that turns on to a holly cow the car just puked all it's oil when you shut it off! mess... I can not explain why it does this. it just does.

So I pulled the head and did some head scratching and realized the one head has an extra oil passage at the rear middle of the head. This is exactly where the oil shoots out when you shut the car off. (from gasket area between head/block)

Looking at the block, there IS a hole that would line up, just like the front hole.. I was able to lower a 12" 1/4 drive extension down said hole so it seems to go somewhere (down to the sump? I think it's a drain) Seems like the only thing keeping the oil from going where it wants to go is the head gasket. If I used a newer head gasket and put it back together (With new bolts of course) do you think it would work?

I would hate to have to tell the customer "You have a 500 dollar head you can't use, lets spent another 500+ fixing the one that was on the car"

Old head
https://www.dropbox.com/s/io447uzjr5...16.11.jpg?dl=0
New head
https://www.dropbox.com/s/5yf3d4mrp2...16.39.jpg?dl=0
gasket
https://www.dropbox.com/s/thi4w8v6w9...17.02.jpg?dl=0
block deck
https://www.dropbox.com/s/x5n7xfyskg...17.29.jpg?dl=0

Little history, car has 61K on the clock, belt snapped at 60,951... I have replaced the tensioners/water pump and belt.

That is the customer's problem. I would just showed them they gave you the wrong one to put on and you did not catch it before installing it. Show them the 2004 head vs the 2008 head. Let the customer deal with the place they bought their rebuilt head from and hopefully they can get a 2004 head in exchange of the 2008 head to put on there. The newer head gasket will make it leak faster it will be fully opened. I do not know if its possible to weld up that valley near the cylinder head bolt goes by to seal it up.

As a service manager, this is a scenario that I dread. You didn't say if the head was supplied fully machined or if you sent the supplied head out for machining. If the customer supplied the head fully machined, I would explain that he got the wrong head and the labour is his responsibility, BUT in the spirit of goodwill I would split it with him and offer to finish the job using my suppliers that would give him warranty on future repairs. I would explain that warranty is given by the supplier of the parts (in this case, him) but any workmanship issues are covered by the shop. If you sublet the machining, the customer is responsible for that too. You don't say if this is a good regular customer or a new customer, and that status can affect how you want to deal with it as well. We recently supplied a good customer with a "free" $12,000 Duramax because the rebuilder reneged on his warranty. If it had been a new or difficult customer, we would have let them sue the rebuilder instead. The problem you face is that the repair will now totally exceed the value of the car and the customer may walk away leaving you with all the incurred costs with no way to recover them fully (or at all). Good luck.