I think a “spec project” should only contains the spec and the functions to support them. If somr spec are strongly related to a project, the two should be kept separated.
Hosting spec on clojars or on a separate platform is a good question. The pro of using clojar is there is only one platform for both sources and specs. On the other hand, it may be less practical to index them on a central website (e.g. to search them, a la Hoogle).
If a reverse index could be built from record/function to spec, it would be a great opportunity to index “similar function”. Since they can be specified at a more precise level than types, it could leverage new version of system.