The IRRS did a booklet called "The 101 Class Locomotives of the GS&WR" The cover page also says Steaming through a century 1866-1966. Its edited by P.J. Flanagan,Ph.D.
It has a couple of side views with no scale and a side, front and overhead section to 3/16" to the ft scale. These are all of locos in original condition.
I bought my copy S/H some years ago for £8.50p so a trawl of s/h book sellers may be in order. I'm also sure the IRRS would have the information you need if they have a librarian to dig it out for you! Maybe need to join the IRRS.
Hope this all helps.