Take a look at the back of your softest tongue there will be a letter stamped or printed somewhere rating how soft it is. A = Stiffest. D = Softest. The krypton rampage tongues are C and I assume would fit the pros. If they would be softer than what you have that could be an option. Otherwise the ilmoro tounges are D i believe but you'd want to check if they fit on the pros.
Not sure who sells them though, try Dalbello direct or see if you can get hold of some used from a beat up pair of old boots on the cheap, the tongues will still be fine.