Yes, this is another tedious question kicked off by HBO's Chernobyl series -- there have been a few interviews and articles (like this one or this interview with actor Jared Harris) where the costume designer and actors discuss how the look and feel of recreated Soviet clothing impacted the show's final look. Harris cites a seamstress from the former Soviet Union describing a sort of hardcore off-the-rack aesthetic for some men's suits of that era, where the range of available sizes was limited and tailoring was a non-factor -- I find it hard to believe this described the whole scope of Soviet menswear options across status lines (not that it's it being touted as doing so!) and I'd love to hear more about menswear or more generally business wear toward the end of the Soviet period. Was polyester really as ubiquitous as some commentaries I've heard on Soviet suiting make it sound? Was this comparable to its use in Britain or the USA of this same era, or would Soviet garment construction look and feel unique? Did this differ by region?
Anecdata: tailored suits and dresses were rather common among the upper middle class in Moscow and Leningrad (dunno about "closed cities" like Chernobyl, but generally the amenities there were quite good), tailored officer's uniforms were quite common for higher echelons as well. I can't really tell if the proper term is "tailored" or "bespoke", as far as I know, the process was like this: client usually brought a piece of fabric (that she got somehow somewhere) to a sewing shop and then tried to figure out what she wants to do with it.
Hard data: according to "Economics of USSR" ("Промышленность СССР") there were 40K official sewing shops in 1970 and 42K in 1980. Obviously, it was possible to order a custom made article of clothing at the *chastnik* (meaning "private businessman", someone who operates unofficially). Revenue for "repair and customized clothes" was 1.3B roubles in 1975 and 1.6B roubles in 1980. Link http://publ.lib.ru/ARCHIVES/N/''Narodnoe_hozyaystvo_SSSR''/Narodnoe_hozyaystvo_SSSR_v_1980_g.(1981).[htm-ocr].zip
In 1987 finland exported 152M€ worth of clothing to soviet union, one item was ready made suits of Turo. Turo also had contract with Marks and Spencer, but likely the stuff that was exported to UK was totally different.
When Soviet union collapsed total exports of clothing sector dropped from 490M€ to 210M€ and many comppanies went out of business as they were unable to compete on open markets.