And only (likely to be) operational branch loco! The GNR one would require, I am told by reliable sources, a rebuild of such massive proportions that it would be (like 90!) virtually a replica engine - and thus holessly uneconomic fo9r an outfit like the DCDR to contemplate.
All three surviving GSWR locos which would suit preservation - 90, 184 & 186 - were substantially altered over the course of their careers. 186 for one, and also 90, lost most of their original components in the 1910s - probably 184 too.