If you're creative, there was a list of names for proposed additional 800s never built... Aoife off the top of my head (my sister's name so it stuck in my memory more than the others). I think @jhb171achill might have info on them.
Re: 'Cultra' edition 800, I believe it's CIÉ dark green with GS lettering, based on what supplies Inchicore had when sending her north.