a few things.
1) 70s rock is great. so posting it is ok.
2) Was there really all that much college radio in the 70s? I can't think of all that much college radio in the 70s. As I understand it, you started having college radio, especially as a distinct style of music in the early 80s. You had punk in 1977, and it was around then when you started having musical styles that diverged from radio styles. Punk got some airplay in 1977, and then you started getting a whole bunch of new genres, some that did get radio play - like new wave - but then you got post punk, hardcore, college rock, all starting from 77-84.
3) the internet and youtube is great because you can find rare and obscure everything. There really wasn't a lot of obscure stuff 50 years ago. The ratio of good but obscure indie stuff today, and even pitchfork is obscure, sorta, to radio is high, but 50 years ago, there weren't 100 unknown but good bands to 1 well known.
You want early 70s rare or at least not basic hard rock? I can do that