Not sure whether I can help you at all. Perhaps someone at the Botanic Gardens would know the answer to this or you could ask someone at the Mitchell Library.
Think I read somewhere that there were old gravestones at Govan Old Parish Church built around 1884 or so.
It seems they had a collection some of which dated back to 10th and 11th centuries.
At some stage there was an old factory demolished in the area and it would appear that some of the gravestones were damaged and then taken to Glasgow University. So perhaps someone at the university could help.
Think the site was something like
http://www.rcahms.gov.uk but if this doesn't work you can try google Royal Commission on the Ancient and Historical Monuments of Scotland.
Hope you get an answer as expect a lot of people are curious.