I believe Massachusetts requires a heavier trigger, but SFAIK there's more to this than just a spring. I'd guess your best approach would be S&W customer service to do the transformation-not being sure the different parts are available outside factory authorized service facilities.

I think you'll like the new trigger, (at least on the 1.0) it's much like an extremely well tuned DA. If you prep your revolver triggers, you might find the lighter pull makes this an unsafe procedure.