Interesting project.
SP numbers 11 and 12 were originally SPC 2-6-0s that the SP converted into a couple of ungainly looking 4-6-0s.
SP numbers 14, 15, 16 and 17 were originally SPC 4-6-0s from the 1880s that got new boilers circa 1915 and these lasted into the 1940s.
Oh, yes the SP did have a number 13 on the narrow gauge. It was the SPC's 2-8-0. It was gone early by a lease to the Lake Tahoe Ry. It had a lower tonnage rating than the 4-6-0s -- that probably a good reason why it did not last long.
Brian Norden