Engine out can I install Dougs beforehand

I didn't read all the replies but I wasn't able to install the engine with the headers both in the engine bay. I had the drivers side bungee corded. Steering column was out (not sure if it had to be but it helped). Idler arm bolt out. Pull center link down out of the way. Drivers side engine mount loose. Passenger side mount disconnected. Jack with 2x4 under oil pan. Slide passenger side header up from the bottom.