You have what you need
I own a 1975 C22. you described the mast step that the factory installs. It may seem flimsy, but all the mast needs is to be held in place at the bottom, and your standing rigging will keep it secure. Catalina Direct sells mast steps that have multiple holes and a ring to attach a boom vang. One thing I would check before raising the mast is if the mast step is firmly bedded to the cabin roof so that you do not get any rain water seepage. Make sure that when you raise the mast, you put the bolt thru the mast step and mast, and do not allow the mast to fall side ways as you raise it, or you'll pull the step from the roof. Use a halyard to measure the differences in distance from mast head to port and starboard chainplates to insure that it's plumb. Allow a litle rake (tilt) towards the rear, so you sail upwind better. Tighten the shrouds firmly, and look up the mainsail slot from below like you were sighting a rifle to make sure there is no sideways bending. If this sounds difficult, it really isn't. My verbal descriptive skills could use a little improvement. After you've raised the mast 1 or 2 times, it will be second nature to you. I've attached a copy of the online manual for a 1987 C22, which is sufficient for your older C22. Safe it in your favorites.http://www.catalina22.org/manuals/mnl87/handbook.htm