If you use a bushing driver the size of the bore, a 20 ton press should move it. If it actually puts out 20 tons, thats a lot. I have bent camber into trailer axles that were 5" round, 5/8" wall thickness and they yielded at 38 tons. Thats the most I have ever seen on the gauge on my 100 ton press. Just make sure you set up correctly when you press and have some kind of guard between you and the driver. I have seen guys use something like a bolt to press with and have it shoot out and go through 22 gauge corrugated sheet metal.
I would consider a torch, but unless you have used a torch a lot, I wouldn't recommend it. I wouldn't poke around in the grease fitting too much for fears of messing up the threads. If you have a drift pin punch that has no taper, it should be ok. A sawzall would probably be the simplest. If you get into the knuckle itself a little, its not going to hurt. It kind of looks like the bore may mushroomed from beating on it. I would try from the other side.
If it were mine, I would measure a new bushing and get a bushing driver just a little smaller and push it out. If you have a caliper, you can measure a new bushing and measure the bore where you have beating on it. If it is mushroomed, you are going to have to ream it out anyway to get a new bushing in it.
