JAZZ ''Buscando America,'' Ruben Blades y Seis del Solar. (Elektra 9 60352-1.) - Panama-born Ruben Blades is a gifted raconteur of Latin life in contemporary America, a kind of Gabriel Garcia Marquez of modern Latin music. Backed by his combo, Seis del Solar (Six From the Tenement), he sings, in his wonderfully nasal voice, jazz that is strongly rooted in Latin musical tradition. It is that feeling of tradition that happily dominates most of this album. By the way, the cover photo alone is worth the price of the album - check it out!