Looking for a 60's japanese sci fi flick...?

Only clues I recall are that one character was a hitman and had silver face paint. He said, "I'm a good shot," at some point. There was a mushroom like monster that was at the bottom of a dry lake bed that was drained by a volcanic fissure in the lake bed. Also, there was a rolling ball monster that rolled around crushing everything in its path. Any help appreciated.