You could try torching it. Heat just the headset cup in the hopes that it will expand and the steering column won't. This will smell bad because it will heat the grease inside, so work outdoors. Heat it some, wack it with a hammer some, heat it some more. Beyond that, if you really want to get this bike working, maybe you could hacksaw the fork off and replace it. But I don't think you'll fit the hacksaw on the fork until you first saw through part of the headset.
Oil is good, grease is better.
2007 Peter Mooney w/S&S couplers/Terry Butterfly
1993 Bridgestone MB-3/Avocet O2 Air 40W
1980 Columbus Frame with 1970 Campy parts
1954 Raleigh 3-speed/Brooks B72