Yeah, I've definitely thought about picking that book up, and I've spent a fair amount of time talking with Gordon Rottman himself for this project actually. His Order of Battle book on the US Army, which is supposed to focus more on smaller unit organization, is coming out in March.
I also found the location of the rest of the Vietnam Pubs on the USMC website:
http://www.usmc.mil/directiv.nsf/HIS...t=5000&start=1