As the spring is inside the tube it simply isn't possible for it to have damaged the chrome directly. A very unlikely cause of your problem could be that the springs are so firm they've misshaped the inner fork leg, resulting in bowing and therefore rubbing. Almost impossible, especially given the springs you've used.
Most likely cause is that you have inadvertently damaged or dislodged one or both of the bushings when you changed the springs out. Depending on how much damage has been done you might be able to fix it by re-chroming the damaged leg, although most likely you will need new forks. Either way, it is very costly I'm sorry to say. As I found recently bushings are not readily available separately for our upside down forks (unlike the Touring) and Triumph only list them as part of the forks themselves. This means your best - perhaps only - option is replacement of the fork leg with a new or used one.