You are doing a great job Sancti.
Could I just add something?
I also have ancestors who are buried in Kirkhill Churchyard and I also have photos of my family graves.
I already knew the location of these graves because I found them in The Monumental Inscription Book for Cambuslang Churchyard
The book was printed in 1972.
It includes a plan of the cemetery, and all the "legible" inscriptions that were on the stones at time of print.
When I photographed my family headstones in 2009, I discovered that some have little or no wording left at all.
My ggg grandparents grave is not on your list, because at 2009, hardly a single, legible word remains on their headstone ... but it was legible in 1972. It is printed in the book!
EDIT: forgot to add
Jackson (from your list) is also my family.
The wording on this stone has also eroded somewhat since 1972
Anne