Dib, I bet you could replace the base with an air ride platform and put the swivel base on top of it without too much trouble. Lots of folks seem to get hung up when the bolt pattern doesn't match. I had '88 Pontiac Grand Am seats in my '89 Jeep wrangler because some numbnuts at Chrysler decided jeep drivers don't need to be able to recline. It took 2 pieces of bar stock and 4 bolts per side to fix that...
I just bought an air ride seat from the bone yard with 5 bladders and arm rests for my new dump truck project (C65 chevy), then noticed a couple really nice air seats on CL for 40 and 50 bucks. I might buy one of them just for the base so I can convert my tractor. That's what got me finding this thread in the first place. Seems like people just can't get beyond a mismatch at the mounting interface. It's not that tricky!