Well willya lookat that? It does take a Village to get to the skinny on this!
If the original HS on this Puch was a Dura Ace from 1976 (and no idea what "UA-100" means cause that does not align with Shimano-speak, AFAIK!) then let's refer to Sutherlands again:
if your properly-fitting HS was say a DA HP-7100 then the stackheight was 39.7...if it was some other DA then might be a shorter SH but I don't see any in Sutherlands that are taller.

So once again: you probably could use a Tange Levin (SH 37.5) and add a 2mm spacer.
You should be 'golden'.