Well if you can be fucked read
http://www.ultimatemetal.com/forum/non-opeth-music-chat/150277-rare-prog-early-70s.html there's crap loads of awesome prog rock to be found in that thread, a lot of rarer stuff too. I'll look through my library and pick out some that I really like which you mightn't have heard. Älgarnas Trädgård, Antonius Rex, Aphrodite's Child, Artcane, Arzachel, Beggars Opera, Blackwater Park, Captain Beyond, Cressida, Czar, Dr. Z, Earth & Fire, Eclat, Fläsket Brinner, Friendship Time, Gentle Giant, Goblin, Grobschnitt, High Tide, Ibliss, Jacula, Kebnekajse, Leaf Hound, Magma, Mahavishnu Orchestra, Nektar, Premiata Forneria Marconi, Procol Harum, Ramases, Satin Whale, Schicke Führs & Fröhling and Spock's Beard are ones that are jumping out atm lol, there's too much winning in 70's prog rock, oodles of great music.