How about the Live at the Rainbow '74 version? It's awesome beyond words and brings out the real 'thrash' atmosphere of the song. An easy place to find that renedition is (and correct if I'm wrong but I think I'm right) on the B-side of 'The Miracle' 7-inch single. If you don't have the single, another accesible place to find it is the Live at the Rainbow VHS which is part of the Box of Trix released in 1992. Of course, search Youtube if you want it really easily. Might I also recommend the Houston '77 renedition - another great Youtube find
I have never seen those before, its about time i started educating myself about Queens early stuff (anybody who wants to can also let me know about early stuff as well)