Before you do all that grinding and all that stuff, squirt some penetrating oil in to the front hole, turn the engine over to spread it around, thread a bolt in to the treaded hole in front of the PTO and use a puller to get it off the stub shaft, the other thing you can do is take two square screwdrivers 180 degrees apart on the back side of the clutch plate and pry the clutch shaft from the clutch stub, if that doesn't work, take a square chisel and drive it in behind the clutch plate and the clutch stub and it will start moving.