I was able to get to the National Archives in College Park, MD last week and I found the Command Chronologies for 1st Guns for the year 1970. They appear to be intact with the exception of February, 1970, which has a few pages missing. Using this new information I was able to flesh out the Battery History page.
For a moment I thought I would be able to locate the unit rosters for the Guns but it appears that when the Marine Corps turned the files over to the National Archives they got lost in the shuffle. They were either mislabeled like the 1st 155mm Guns files were or they were not included. I’m not finished with the National Archives yet. Now that I am a registered “Researcher” and I know my way around there a bit, I intend to get back there one day and delve into the unit roster files a bit more.