Originally Posted by baxtefer

this part is wrong. uniglide and hyperglide have different splines.
Hyperglide cogs have one wide spline and will not fit on a uniglide freehub unless you file down the spline.
(uniglide cogs will fit on w hyperglide bidy though)

you can use most spacers (or some PVC pipe) and yes, you'll need to use the small cog as the lockring.