the odds of it working are significantly lower than with a non-turbo-cache model. i seem to recall that the early turbo-cache cards were still using full-size cores (nv43), but all recent ones have changed to a 4-pipeline gpu that has no unlocking capabilities (nv44) and overclocks less too.
i might be mistaken in that belief though, and all turbo cache cards were nv44 from the start. it'd make more sense that way. in any case, i don't think it's worth the risk when a full 6200 or better yet 6600 isn't that much more.