Cleaning leather seats submerged in flood

I have a set of leather seats from a pre-1994 Jeep Cherokee XJ (agate/medium gray) that appears to have been submerged in floodwater. There is a lot of fine silt in the cushions and seat cover seams. I want to clean and recondition them, what’s the best method/cleaner to use? I already plan on completely dismantling everything, wire-brushing any rust on the metal pieces and re-spraying with rustoleum or similar paint.

I have also successfully disassembled three motors in the power base, brushed out the fine silt, lubed and reassembled and now they work perfectly. I purchased some other stuff for my Jeep and the seller threw the seats in for free. They were in a shed on his farm for several years, not being rained on, but also not being taken care of very well lol. I did not realize they wouldn’t fit my 98 Cherokee until I had already repaired the motors so I figured I’d take a swing at restoring them to a usable condition and try to sell them on Facebook marketplace… then take that money and dump it into my favorite money pit ;)