Six cylinder torsion bars with big block

Have a 440 in a 69 Cuda that was originally a 340 Formula S car it is a dual purpose car that runs 10:18's thru the muffs, batteries in the trunk but it's iron headed. It still has the small torsion bars on it and on more then one occasion it has almost gotten away from me on the street. Do you have to upgrade the bars? No but there's lots of things you don't have to do. From personal experience I plan on adding the larger bars just for piece of mind and to make the car more manageable on the street.
My two cents!