It took a while to figure out the right parts to do this, so I thought I’d post all that in case it helps others. I had to find just the right pedestal to fit the existing holes in the floor. In the end, everything was a simple bolt-in and the actual installation only took a few minutes.
Seat pedestal:
Garelick Smooth Series 15”, #GAR 75415
Seat swivel:
Garelick Anodized Spider Top, #GAR 99023
Seats:
Springfield Folding High-Back Seat, white: #1040649
Total cost was about $350 for two seats, one swivel and one pedestal. The seats came from West Marine and the pedestal & swivel from Fisheries Supply.