Assuming you want to re-use as many parts as possible, and need everything apart to inspect for unacceptable pitting.

Use Evaporust as a multi-hour soak,
but be prepared to repeatedly brush the steel surfaces to help the process of removal.
Technically Evaporust removes some carbon content from the surface of steel, making a very thin layer slightly less strong.

When things are surfaced cleaned
buy dry ice (from a supermarket that caters to fishermen, or welding supply store)
and have an electric heat gun.

Heat the aluminum piston
and keep packing crushed dry ice inside the steel pins.

Get the piston hot enough,
and the pin cold enough
that you can take them gently apart with gloved hands.

Discard pitted pins.

Polish con rods with shallow mild pitting.
The polishing will also remove the thin layer of reduced carbon content.

Discard any con rods with even a single deep pit.