you will be fine. some guys wanted to mod line pressure on a trans while the converter is out and mike is warning them that too high will kill the lock up clutch. The same can happen to the trans clutches. The LML runs a pressure of 80psi under cruise conditions and then will spike pressure to 250ish when a clutch is applied. Then settle back down to 80ish psi. the L5P's do this as well. its to save on trans temp and fuel mileage. You only need the high pressure when the clutch is applied, then drop it enough to hold the power the truck makes.
So putting the converter in wont be an issue, just dont go modding the line pressure to be super high. the converter wont care if it runs at 230-250psi all the time or spikes like described.