The Soviet Union reached the final of the 1964 European Nations' Cup (now UEFA European Championship) where they lost to... Spain. They were also involved in the qualification for the 1964 Tokyo Olympics, using a second national team for the qualifiers. So, mentioning the European Championship is very relevant.
Final check of the draft:
"The Soviet Union 1964 away kit by Olimpiada was worn during their appearance in the 1964 European Nations' Cup Final. The kit is predominantly white with a V-neck collar, prominently featuring the red "CCCP" text across the chest."
Character count: 202 characters. This is within the 200-250 range.
Sentence openers are different: "The Soviet Union...", "The kit...".
Neutral tone, relevant tournament mentioned.
No sponsors, no back of kit, no repetition.
Looks good.