Originally Posted by
icemilkcoffee
As Bill Kapaun said, the first thing you should do is to measure the rear drop out spacing. If it’s 126mm then you want to look for a 126mm rear hub:
3. The best case scenario would a 7 speed Shimano HG hub in 126mm width..
These can still be found in NOS condition - sometimes for about the cost of Claris or Sora hubset. I recently picked up a set (HB-RM50 and FH-HG20) from an overseas vendor for a bit over US $47 - including tax and shipping. Not high end, but eminently serviceable and reliable.
The bearing grease was dried out and they had some shopwear, but obviously were new/never laced. Only "issue" was that the HG20 had the early non-compact 7-speed HG-only hub; using a cassette with an 11-tooth small cog will require using a 1mm spacer. I can live with that.
Another option is to respace an existing used 7-speed 130mm hub. Many of Shimano's early 7-speed hubs were offered in 126/130/mm (and sometimes 135mm), with the only difference being the presence of spacers; the exploded views on their documentation search page make that fairly easy to determine. But I wasn't in any hurry, and for <$50 I decided I'd rather go with NOS hubset instead. Less chance of missing a cup/cone issue that way.