Wastegate actuators are difficult to change with engine in, changing the actual wastegates (which is what we just had to do) was engine out. You need to get the turbos off to machine out the wastegate port and add a larger flapper and the engine came out. (Note this was on GT28RS which are probably a bit bigger but the principle should be the same)
We considered a lot of options to avoid this, but in the end the engine came out.