Smeds "some' as in very obscure" had an off ball 16 inch , when requiring replacement the parts they superseded to the complete 17 inch unit. Weird quirk production line supply I suppose?. I had four brand new complete rear wheel sets that were taken from postie bikes and replaced with 17 inch sets prior to release. Thought a couple would handy as emergency spare sidecar wheels on the outfit. Both gone to VMX heaven now ....crushed by umm the 754's pork.... Other two adapted to uses like above request. Cheers.
Paul , light weight 17inch would be a far easier to source and convert I think you will find.
Here is a resized wheel bike( 14 and 17 honda) ,made from SL70 left overs, adapted SL100 front forks and triples and a Chinky 138cc engine I chucked together one afternoon. Note the stand extension to get an idea on raised height.