If you use a washer, best to reinforce every hole with a product made for this. Sapim’s oval shape makes sense to me. Personally I don’t use vintage rims for any of my bikes except for a set of modern Velocity Synergy rims that needed a hub. Most of my stuff has polished Sun CR18 rims. Cheap, durable, good looking.
https://www.ebay.com/itm/8-x-SAPIM-S...9013883?_ul=IN
oops, missed the 650b part. Yeah, rims are spendy