SUCCESS! Thank you all for your ideas. The pin is out - Basically I finally used a rosebud oxy/acetyl for heat while pressing it with a 20 ton shop press. I only used the heat once sparingly until the pin moved slightly, and then went with only the press as I was nervous about the steel temper. Overall, progress was slow about 5 pumps on the jack and max pressure for a few millimeters, and once the pin was into its hole I had to use spacers because the press head was too big to follow the pin into the hole. One inch steel nuts worked for spacers. One hack that worked was whacking the opposing side of the coupler with a 12lb sledge a couple times when it was under pressure - you could feel the pin sliding. There was suprisingly little rust or dirt or grease on the extracted pin - just some very low corrosion; and very thin patches of grease, with some patchy metal to metal contact polishing.
Next comes cleaning and polishing and reassembly. I am thinking of machining the pin - cutting a slight groove around the circumference at the Zerk and an intersecting longitudinal groove the length of the pin on the side opposite of the zerk to help distribute grease, and taking a few thousandths off the diameter overall.
I learned some things (but don't want to do it again!) like how rosebuds work, about clay content grease, what a welding cutting rod does, how to ruin a 20 ton press, the beauty of a 12 lb sledge, solvents don't help a stuck pins, how to bend one inch grade bolts and nuts, and what a great forum this is. Thank you all again for your help!!