Here's a list of stuff sold as LSD during the '60s and '70s-
http://www.erowid.org/chemicals/lsd/lsd_history1.shtml
I think the acid back then was a bit more potent on average then it is now. The trouble is that most real hits back then were around 50-100 mics, but every so often there's one that's 300-500 mics. So you get used to taking 2-4 hits of the normal stuff and then BAM, you get totally blown away. Taking doses greater then 1 mg was fairly common back then, according to Grace Slick 600 mics is a "decent" dose of acid. In "Be Here Now" Ram Dass talks about giving an Indian guru 1,200 mics of sunshine acid (specially pressed for Ram Dass and measuring in at 300 mics each) and seeing the guy go basically unaffected, which is incredable. I've heard a lot of stories of people taking very high doses of acid back then as a fairly common occurance.
Here's a guy who's responsible for turning on several major figures in the 1960s acid scene-
http://www.erowid.org/culture/characters/hollingshead_michael/hollingshead_michael.shtml
He got a gram of lsd and mixed it together in a mayonnaise jar with icing. Apparently his first trip was from licking the spoon he'd used to mix the stuff. According to the erowid page he made 200 ug doses, but I've read stuff that said that he sometimes would give someone a heaping spoonfull of it for a trip.
I can't remember where I read this, but I think it was in a biography of Timothy Leary. According to what I read (or heard, I really don't remember where and I can't find anything about it online), Timothy Leary's son would sometimes take upwards of 10 mg of lsd. I read in his biography that when Timothy Leary was doing the commune type deal he would dose acid out, but refuse to tell people how much he had dosed into the medium. During one period he would dose people by dipping a stick into acid solution and having them lick it, and another time he had some alcohol bottles that were dosed with acid sitting out for people to take as they wished, but he refused to say how much the doses were. Timothy Leary was a reckless asshole who really fucked things up in terms of psychedelic drug law and the 1960s in general.
Here's another archive of blotter hits from the late '70s and the '80s, and the acid in it is notably weaker (generally) then the stuff in the 1960s. There's also a lot less of the high dose hits then there were in the 1960s and '70s archive at the beginning of the post.
http://www.erowid.org/chemicals/lsd/lsd_blotter_microgram_1987.pdf
If only acid was legal, we could know how much of what substance we were taking when we dosed.