Had my cam chain done but...

[savvy]

Maybe sounds a bit daft but!!  Have you checked how much you need to tighten the water pump up? I have had a time when the pump would not sit flush due to shaft pump interface. What it was that the pump required a lot of preasure to screw down. when I took a bit off the shaft,about 0.020" I could push the pump tight on without the screws so only needed a nip up to get it seated. Just a thought? try 2 gaskets see if the noise goes.