HI Emily, since you know your father's unit, the best source of information are the unit Morning Reports. These would document the day to day activities of the company, including personnel changes, location, and brief descriptions of the unit's action for that day. These are held by the St Louis Archives, which unfortunately is still closed to the public. When the archives reopens, you can put in a request for your father's service records but most were destroyed by the 1973 fire. Right now the archives are only addressing emergency requests for veterans. I'm guessing you have his separation papers?
Since the 325th was part of the 82nd Airborne, there are several narratives that describe the action of the various units in general. Some of these include tables with glider landings, so you might be able to get an idea of when your father landed in Normandy. I found these documents at the Ike Skeleton CARL digital library (https://cgsc.contentdm.oclc.org/digital/collection/p4013coll8/search/advanced). My dad was in the 320th Glider Field Artillery Battalion of the 82nd. I can send you the narrative for Normandy and anything else I have that might mention the 325th GI. Again, these are not specific for individuals, but would likely describe the 325th actions. Hope this is of some help. joan