Yes, you have enough upgrades to defeat Galdon. First you circle around to his back and whack the glowing area a few times with your staff. He will then swallow you. Hit the thing in his stomach containing the spellstone a few times and he will then cough you out. Assign the fire upgrade to the Y button. Back up into his green fireball range and hold R. After several fireball attacks he will start sucking air into his throat. This is the time to fire at the green glowing area. After you repeat this process 3 more times he will swallow you again. Attack the thing in his stomach a few more times and you beat him!