I'm resurrecting an old tri bike for a friend and found the galvanized shifter cables rusted away.

I can't seem to find any stainless replacement barrel end cables for the Ultegra bar end shifter assemblies. I see a bunch of galvanized ones on ebay but no stainless.

Three questions, where to get them, what diameter (1.1, 1.2), and is it as simple as pulling the old cable back out of the housing and sliding the new one back in?

Thanks
Ron W.