Look in the BGB. It will be a big job. Only 10 bolts holding the head on but you'll have to take off all the stuff attached to it. You'll need a torque wrench, new head bolts and a lot of patience. You also need to wonder about why it's blown, you should really check for warpage etc..
well it actually runs fine with no contamination, just previous owner had it tested and was told co in the coolant so suspect its gone.
doing new
rad
thermostat
waterpump
all at the same time so hopefully will solve prob.
only over heats on prolonged hard boost
part of me wonders if its just a naff rad and a stuck open/close stat