What the hell is annealed?Was the copper gasket properly annealed?
I would give it another go using better nuts, inconel studs and either tab washers or NordLock washers before going to the expense/hassle of getting the manifold and turbine housing ground perfectly flat to be able to run without a gasket. Looking at that manifold flange face it needs a lick over for anything to seal regardless
What the hell is annealed?