when i had to change out my radiator and AC condenser due to a slight miscalculation on a rally i was on, I just ran the car with the radiator cap off and the heat blasting. After the engine reached operating temp, I made sure the radiator was still filled and then put the cap on it. I have not had any problems since I did that. Best of luck to you on this swap. I was amazed when i removed the rad and condenser how much room in front of the engine there was. I was also able to get in there with a toothbrush and degreaser and remove some rode grime.
