Check out Elvis in is own unfinished martial arts documentary on youtube. Just do some Elvis/karate searches. The "king" takes a real beating, no wonder he couldn't finish the film. He sure didn't look like a beginner but who knows what his real skill/ability was.
Elvis started out breaking popsicle sticks in half he worked his way up too broomsticks then two by fours. Then when an intruder or burglar came to his house he broke the door down and ran for help.
Not sure but I know he trained with Ed Parker and Ed Parker's number 1, my great uncle Thomas Kelly.