I dont know of any official communications to KHs regarding contents of the library, but in mine they have lots of old stuff inc studies in scriptures vols 1-7, many OLD books and many OLD WT and awakes. We had several older JWs die over the years and their old publications come to the KH library if not already there.
I err "borrowed" some of the books over time during my research and then returned them when I'd finished. I didnt bother asking in case they said I couldnt remove them. That would have made reading them and research nigh on impossible so i didnt ask.
Volumes 2 and 6 of studies in the scriptures were what I read.
If your KH doesnt have them try asking some of the oldtimers in the hall if they have the books you want to borrow...
What I DO find very suspicious though is the LACk of older WT and Awakes and publications on the WT CD! Kind of makes you go hmmmm. There is PLENTY of room on there for them, or else release a 2 disc version or even (shock horror) a DVD... but no. The WTS doesnt like to make it easy for JWs to realise it's all based on wrong chronology and a wrong premise so they dont let us easily have access to those older publications for research.