I think that packing was for earlier water pumps that had a packing gland nut that could be tightened around the shaft or the packing could be replaced.
You'll have to change the water pump. I got a rebuilt one from NAPA for around fifty dollars, plus core charge. I just removed the water pump from my '46 216 today. It's too hot here to for me to do any more today. I'll be pulling the radiator out also because I think it had a leak also. I'll have it checked at a radiator shop.
Let me know if you want the NAPA part number.
Before you pull the pump make sure it's not a leaking radiator hose. I changed the heater hoses and I'll change the radiator hoses since they were cracking. They hadn't leaked yet but they needed to be changed soon anyway.

Jacques

Union, Justice and Confidence