Well, I know that they were together around 1967/1968, but they could have been together for a longer time (like 1967-1970, or 1966-1972, who knows).
Frankly I don't know that much about Patti Dahlstrom either, I only have two of her songs. She made 2 or 3 albums in the early to mid seventies, and 3 or 4 singles. Based on what I heard, she had a pretty good voice.
I think I've found a way to contact her... I'll try to ask her whether she'd agree to be "interviewed" (by email) about her career and her relationship with Bruce.