Oh god I am so sorry, I absolutely love the ponies you posted, but once I saw them I had to go make my own attempt at them using the designs I usually use for Crowley and Aziraphale.
I took some time to do extra specific tweaks beyond just adding the cutie marks, though sadly the resolution of this will always be small since it's made from screencaps....
And there's also a version with the vest AND the tartan scarf, if anyone wants it:
http://lupous.net/srsartistkat/fanart/goodomensponies-wvestnscarf.png Also now I really, REALLY want to see somebody write fic where these two have to travel to Equestria from their own dimension in order to find uhhh...a book or something? IDK. Aziraphale vs. Twilight Sparkle over books would be amazing....also it would just be super funny to see these two as ponies. "Well I guess this is the dominant life-form in this dimension..."