I saw one of those in a junkyard when I was about 18 and I wish to this day I'd tried to get it. The DeSotos are big enough to make power but small enough to fit in quite a few places.

More than anything else you need patience to not break anything while you're trying to get things apart. And a mess on the floor isn't necessary if you take precautions. I'm going through this right now with a 59L Ford flathead block. Even though you're going to replace things, try not to break stuff as you're disassembling the engine.

Kroil can help, or Gibbs penetrating oil. It took several days of pouring Diesel fuel into the spark plug holes on my 1928 Allis-Chalmers E to get it free enough to spin with jerky applications of the clutch while being towed by another tractor.

Getting the crank out seems like a good first step.

If you're going to try to push pistons out push on the underside of the piston head or on the wristpins. Pounding on the connecting rods can have bad results.

Lye solution will eat the pistons if all else fails. Put it in a hot tank for a week.

R.

On one engine that had a head gasket failure leading to pistons being glued into the block by the burnt anti-freeze, I used a length of rebar to blow off the piston tops and then jacked the piston using a 50-ton hollow core jack with 5/16" wire rope looped around both sides of the wristpin. The wire rope went through the jack with clamps on the top. After the pistons were jacked up to deck height they drove out from the bottom with a 2x2 and dead blow hammer. This block cleaned up at 0.020 over.