78 hub is different. TS185 uses the same wheel/hub as 125b except the rim is steel so there is plenty of easy options to get another hub but finding a good used alloy rim is a lot harder.
How good do you need the rim to be? I got one, no dents or cracks but needs a lot of sanding and work with a file on tyre lever marks etc. I think you could get it looking 'respectable' but if you want it better than that (which i did) then you will have to get a new or very low use rim. What i have would not be good enough for a top restoration.