The washer issue has worked out for me, thanks to the clarifications here. Unbeknownst to me until exploring this, the bike's PO was using the thicker spacer washers as the nut washers, but without a cowl. I had a pair of the thinner, chromed, nut washers in the spares bin, so, I've been able to assemble the mockup. I guess I'm within a few thou of hooliganistic enlarging of the cowl holes but a PO of the eBay cowl already took care of that and I think it will be fine.
Richard L.