Yeah, Bob Rafelson (IIRC) has said that they called the movie Head in the first place so that they could advertise the next movie they made with the tagline, "From the people who gave you head..." (But then nobody saw Head, so they changed their minds when it came to the next film they produced: Easy Rider).
It's on the BBS Story Box Set, which I picked up for a song on Blu-Ray a few months ago, but I haven't watched more than the special features yet. It looks pretty incoherent (as one of the Monkees said at a recent concert: "We're going to be projecting images from Head; if you haven't seen it, they won't make any sense, and if you have seen it, they won't make any sense, either.").