New motor, sounds awful?

Here's an update on this saga.
The old boy rang me tonight.
After a two week summer Vacation (yeah, southern hemisphere for the win!) he's pulled the engine out of the car again. He said he had trouble turning the motor over by hand.
So out it came.
And as it turns out, one bank had the pistons back to front. It's running icon forged pistons, and they have one small relief, and one larger one. we can only assume that with the block being upside down, he got mixed up, and fitted the one side the wrong way around.
No wonder it sounded so hideous. So engine will be getting stripped down tomorrow. And the inet valves from that bank will be spun in the lathe with a dial indicator to see if they need to be replaced. (If i was a betting man, I'd say yes) As well as all other clearances wil be rechecked too.
Here's hoping that the valve guides haven't been split too. I'd say with the heads being iron, there's less chance of them having been damaged than in say the instance of a cam belt failure with an aluminum head..