Small block keeps blowing the oil filter off?

I just fired my 360 I swapped into my '76 duster, and I heard a pop, then oil went everywhere. From the pass side where the filter goes onto that plate. I suspected the Fram filter, because I've heard not to use them for any high RPM use. (Racing) I took it off, and there was nothing wrong with it, but I swapped a Purolator one, and topped off the oil. I fired the engine again, and if puked oil all over. I don't have the 90* adapter on the engine, could there be something behind the flat mount plate?
Mike