I have a handful of Sun Tour Spb Pro and Sprint JIS headsets headsets. I also have spare crown races so can subsittute a 26.4 if you wish. PM me or email me through the Chain-L site if interested.
The other alternative for you if this is a nice bike you plan to keep for many years is to have the frame reamed to 30.2mm so you have your pick of headsets in the future. Any decent mechanic in a shop that sells road bikes should be able to do this at a reasonable price.
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