Ah, from the link I posted, there is one for a 2.8C (or so the seller claims, I cannot tell, since I don't own one).
It's pretty damn ugly and beat up, perhaps way to beat up?
https://www.ebay.com/itm/Rolleiflex...181430?hash=item4d43df2d76:g:MZ0AAOSw0OJXL3aF
Cheap though (from India)

- With some refurbishment it may be usable, that one lacks the magnifier-glass though, which I feel is pretty essential to be able to shoot properly with these cameras..
I would consider getting a better ground-glass for it though, as the one in the link here, looks pretty funky (not sure if the proper screws follow the item, if they are anything similar to my Rolleiflex Automat, they are short, small with fine threads.
Anyway, just wanted to help out, I hope you get it all sorted in time ^^