The themed Beach Boys best-of Summer Love Songs, out yesterday, promises the requisite uninspiring “new studio mixes,†but does have one genuine gem: the second-ever official version of Dennis Wilson’s “Fallin’ in Love,†a song previously unreleased in the U.S. and out of print in the U.K., where it was put out in 1970 as “Lady.†It was recorded during the sessions for seventies Beach Boys album Sunflower, and predated Wilson’s acclaimed solo debut, Pacific Ocean Blue, by seven years. (His only completed release; Wilson drowned in 1983, at the age of 39, in Marina del Ray, California.) The Beach Boys are all about unreleased treasures, of course — most notably SMiLe, finally heard in 2004, but also Wilson’s second solo album, Bambu, partially released along with the 2008 Pacific Ocean Blue reissue. Still, “Fallin’ in Love†holds its own — it’s an absolutely gorgeous song, full of swelling, understated strings and Wilson’s proud emotionalizing, that is, at least according to one website, maybe about cocaine.