Joe Gilbert died in a car crash in Los Angeles on August 6, 1966. Eddie Brown tried to continue as a solo act, but didn't succeed. (The All-Music Guide says Eddie died June 14, 1974, but something makes me think they may be mixing him up with another Eddie Brown.) In 1967, GNP Crescendo came out with a very nice album called The Best of Joe & Eddie (click) which is now available on CD.You can find samples from their CD here (click). I can't say I really like their recordings - they're just bit too "commercial"-sounding.

I don't have any first-hand California knowledge of this group. I hadn't crossed the Rocky Mountains until 1970, when I came here to California from Wisconsin.
-Joe Offer-