By design the pressure relief bypass built into the pump should protect the system. I was curious how much protection was built into the correct pump so I did a little reading. This is from the MB service manual page 405/1

In addition, the pump has a pressure relief device in the shape of a bypass which disconnects the suction and delivery line at approx. 5 bar overpressure.

5 bar is ~72 psi. For comparison a walbro electric I'm using for another megasquirt project hits max pressure at ~140 psi. which is quite a bit more.