I don't know if thinner 27" rims are available, but I love the polished Sun CR-18s on my vintage bike, they fit with the overall look of a vintage bike.
If you want narrower rims, you can consider moving to 700c as long as your brakes can extend another 4mm or so.
You may be able to find an old set of 27 x 1 rims, but there are even fewer tires for the narrower profile than the more traditional sizes (27 x 1 1/4). If you want to trade for rims, or pay for access to the sale/purchase subforum, check in Classic & Vintage... someone may have what you want.
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Slow Ride Cyclists of NEPA
People do not seem to realize that their opinion of the world is also a confession of character.
- Ralph Waldo Emerson