Swap to power disk ??

You'd need a booster with an A body bracket, master cylinder, and a new brake lever push rod.

But personally I'd skip it. I have power disks on my challenger, and manual disks on my duster. Of the two, I much prefer the manual brakes on the duster. They work just as well and don't have the vague, soft feeling that the booster gives. Sure, the pedal effort is a little more on the manual brakes, but with the right master cylinder its really doesn't take a lot of "leg" to get the car stopped even in a hurry. Eventually the booster will come off of the challenger and it will be swapped over to manuals.