That little bit of rust..... meh....... Get the crank out of the way and knock them out through the bottom. Spray the cylinders with wd40 and they will come out.....
I have pounded pistons out of motors that sat opened in the pouring rain for who knows how long and the machine shop I used never had any problems. No matter what you do an oversize piston is in the future anyway....
Good luck,
JW