In her TAMU Master's Thesis, "Analyses of Genetic Diversity and Relationships in the China
Rose Group," Valerie Soles analysed the genetics of (among many others) a triploid rose they'd gotten from Ralph Moore as Slater's Crimson China. http://repository.tamu.edu/bitstream/handle/1969.1/ETD-TAMU-2009-12-7450/SOULES-THESIS.pdf?sequence=2

On page 37, she says about that rose, "A rose that did prove to have the same profile as ‘Slater’s
Crimson China’ was the found rose ‘Ferndale Red China’ (C38), so it seems that rose
has found its identity. However, there is more than one plant identified in the trade as
‘Slater’s Crimson China’ (Piola, et al., 2002), so testing multiple sources could
investigate the different clones in the trade, but would still not be able to say with
certainty which were the original cultivar."

Since Moore had a decades-long relationship with Huntington, and one of them may have gotten it from the other, this seems like another indication that Ferndale Red China may be Huntington's SCC.

Huntington Slater's is a red or cerise red China distributed for a period as Slater's Crimson, but it is not that cultivar. It was found in Virginia by Carl Catto. Later it was found in California and Texas. It has also been called informally, California Slater's.