I think all the PB guitar necks have a 12" radius.

It's certainly possible to reduce the radius, but it's a frets-out/nut off job and really needs to be done before the neck is set, otherwise you're at risk of damaging the top around the neck. Though with masking and being careful, it is possible to do.

You can get pre-made radiused wooden sanding blocks, and then its just a question of lightly gluing sandpaper into the block, rubbing down and going through the grades.

The smaller the radius you go for, the more of the wood at the side of the neck you will take off, so you may find that you sand the edge off some of the dot side markers.

You'll need to get new fret wire, and either buy it pre-bent or bend it yourself to suit the new radius. You may need to cut the fret slots a bit deeper as well (with the correct width saw), as the depth at the sides will have been reduced. Once the frets have been inserted, you then need to cut the fret-ends off, file them at an angle, then do a fret levelling, reprofiling and polishing exercise.

A re-fret job isn't to be taken lightly, and you really need quite a few specialised (and fairly expensive) tools to do it well.