LBZ with 200% & BW S467.7 Turbo

Just thinking out loud and trying to wrap my head around the logic. Was asked to tune this truck in the spring on my dyno and had a few questions. Truck has a 12mm pump and Exergy 100% injectors so I will be good on fuel but airflow limited for horsepower. Turbos with no VGT have basically have no boost control and I see most people don't run wastegates. So in my logic more fuel heat is more boost. Assuming that is how you control boost? If that is the case how much boost is too much boost assuming the bottom end is built? Every turbocharger has a max shaft speed but without a shaft speed sensor how do you know? Assuming monitoring EGT & drive pressure is good to do. Sorry if I sound clueless coming from the petrol world