Thank you, the block was in excellent condition and I didn't really want to bore a perfect block, so all that was done was honing.
I was concerned about noise but I still went for 2618 because of the pistons themselves as I had feedback from other people and I heard about a particular incident where the turbo was blown to pieces the pistons didn't have a scratch, so I was impressed. It's also the best option for this engine according to my mechanic, at least from all projects he has built. Furthermore I don't notice any piston slap, even on cold start, just some blow-by during warm-up.
It was the valve cover gasket.
The turbo is the RTMG IS6XX ball bearing (GTX3076R GEN II) that is rated for over 600hp.