340 stroker pistons

As was said, have it sonic tested first, and .060 over 340 bore is typically going to be more expensive with any manufaturer because it's usually not a "shelf" part number like std or .030 ones are.
As far as why would you... Well, the 340 is an rpm engine. But a street car generally isn't. The 4" stroke makes the 340 feel like a 440. They really are brutal torque engines.