It's not about Parelli or any other approach. It's about work, patience and consistence. Parelli may work for you, or may not work for you. In any case if he's healthy and you are unsure about riding I'd start working with him on ground. You may work him out first (like lunging) and THEN bring to the grooming area (when he's calmer and more focused on you).
BTW, you can start adding calming supplements to his diet to quiet him down a bit.
"Life isn't about waiting for the storm to pass: it's about learning to dance in the rain..."
"When we are no longer able to change a situation - we are challenged to change ourselves."
"How people treat you is their karma; how you react is yours."