Looking good there my man! That REALLY sucks that you have all those stuck studs in your heads
I think you're going to have to drill, but who knows, you might get lucky.
Be careful with the oil pump housing removed, as that supports the front of the IMS shaft, and the chain tensioner in place on the 4-6 bank as it's yanking the end of the shaft toward the head. You'll almost certainly have to remove the tensioner on that bank to get the oil pump housing back in.
As to intake stuff, I will never give any of those companies a dime of my money. I've installed plenty of those things on various cars, and I can assure you that their profit margin is fantastic for the crap engineered stuff they sell.
Removing the secondary air BS and running RoW software is one of the best things you can do on these cars I swear.