You're on the right track for the grinding and removal of the ball...some are not so bad to remove and others can be a pain. Don't drill more than the diameter of the ball's stem, naturally. You'll need a two jaw puller to remove the pitman arm...you may be able to borrow or rent one from O'Reilly's or AutoZone.

Since you're using the new balls that are threaded with retaining nuts, file or grind two "flats" in the shoulder so you can loosen those nuts and rotate the balls 90 degrees every time you grease the frame (or change oil if you do it yourself). That way your new balls won't go egg-shaped. Good luck!

~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end