You should still be able to find TA rings for the TA Cyclo Touriste crank (try Harris cyclery) and those are a good match on a classic Swiss bike, I reckon. Big range of sizes for that crank, you should be able to get the gear you need for Seattle...if the shop can't work on old bikes and parts, find another shop that can. Or (better yet) learn to do it yourself...it's one of the beauties of owning a classic, and not that difficult.