Unsurprisingly, that‘s something I considered, too, particularly after someone who knows these unis well told me that the rims they used weren‘t particularly strong (I think the unis were mostly made for use on tracks or in gymnastic halls).
I haven‘t taken the uni apart yet, so I don‘t know what bearings would be needed. My visual estimate is the OD is considerably smaller than todays 42mm standard, so I‘d have to make sure to be able to acquire fitting bearings - or make new lollipops (which I won‘t).
Honestly, I‘d like to keep the une as stock as possible, except for the seat; that needs to be replaced anyway, and I want something more sensible - in my opinion - than what they used originally.
Anyway, thanks for your suggestion. Even if I keeping saying „no“ to propositions from you folks, I appreciate the fact that you put some thoughts into this and make suggestions.
I really need to post pictures of this uni in the „my projects“ thread - I‘ve taken some a couple days ago.