Do as others have suggested. I have seen flywheel pullers made from thick steel plate, and a several ton bottle jack. These flywheels are stubborn on the Regular and F20 series. I gave up on mine after trying a puller that was lended to me, AND using a liberal amount of PB Blaster with an Oxy-Acetylene torch. Wouldn't budge.
If you google Farmall F20 Flywheel Puller, you will see many versions people have used in the images section. It is a project to get it done, and then pressing it back on is another project in itself.
Let us know how you handle it, and good luck.