Billet Hub Question...

Well it can be done on the front without too much trouble. I've set up a couple of cars with Viper brakes (rotors + calipers) but in both cases we redrilled the rotors to work with 5x4.50. But the hubs could be set up for 6x4.50 without any issues. You do have to figure out where you want the wheel to be mounted for clearance reasons and then design the hub around that location. Then once the wheel is mounted you have to figure out if the caliper can be fitted.

Which type of Viper brakes, radial mount or ear mount? The late model radial mount is the way to go if possible. I sell kits to hang either Viper brake system on most any Mopar muscle car but the kits are all designed around 5x4.50 bolt pattern.

Hanging the Viper brakes on the rear is a lot of work. You'll need to design some sort of backing plate adjuster system plus get custom made axles. The Viper calipers are fixed which doesn't work very well with the tapered roller bearings so that needs to be addressed.