Those newer G-body platform seats tend to be a bit wider frame-wise than what naturally fits in the floor pan of a B or D body like this, but anything can be done with considerable work and figuring. Essentially, you'd need custom frames I believe, if the overall seat dimensions themselves fit. Same goes for the wiring and such. I believe there's one Caprice wagon around here with either DTS or Seville seats, and they look great, but it was not an overly easy swap.
That's actually why '99 and prior Pontiac Bonneville seats have become one of the most used, as the floor pan and therefore frame of those seats is an almost exact match for these cars.