Depending on your frame's inside width, how many speeds (shifter) that you would like to use, a period-looking (i.e. skinny barreled) hub might end up being an actual vintage hub.

Shimano's freehubs, even their lowest HB-RM40 and the like, are very durable and can give very long life. 7s versions are plentiful at bike co-ops, and really cheap when/if the rim is in bad shape. Both 32h and 36h are common.

Getting up to the old DX level (mtb, touring) and Ultegra level (road) versions, seals are first-rate and the bearings very, very smooth.

I dread the day that such hubs become hard to find, so I try to keep a good stash of them on hand.
As of 1996, with introduction of 9s gruppos, Shimano's freehubs eliminated the stepped bulge in the hub center and made all of their top-level (105 and better) hubs lighter. Their mtb hubs had grown fat centers by this time however.

As for your Nishiki's rear freewheel hub, you will need to remove the freewheel and axle in order to diagnose the problem. A broken axle, cracked bearing cup or disintegrating cones or balls could all be factors in a noisy, rough or loose turning action.