Ed, if the PTO is pretty well hopeless, you might be able to get it off by taking the front pieces out and accessing the end of the crankshaft. The body of the PTO in front of the clutch disk rides on a large ball bearing pressed onto the crankshaft, and the setscrews dig into a ring just behind the bearing, which is set into the inner race of the bearing. If you have a reinforced gear puller, you might be able to just drag the whole thing off that way, though you will probably leave some marks in the crank, and possibly ruin the bearing. You might want to try this link as well:
http://members.aol.com/pullingtractor/misctips.htm#ptoclutch
http://members.aol.com/pullingtractor/misctips.htm#ptoclutch