So a couple of questions.
1. What year is your boat?
2. Do you know the difference between a original, new design, mark II and sport variations of the C22?
If your boat is of an original design then someone has updated the mast step. the stepping base is for the New Design and the ring is for your vang. The block is installed to accommodate trimming the mast incase someone broke out the old hole during a stepping so that the mast retains its original height.
If your boat is a new design or has a new Design mast (oval sides not round) then the block may make the mast too tall. The New design boat has a taller cabin top and a shorter overall mast than the original masts. So you use a block on an original design boat to retrofit the new design mast but not on a full length (uncut) mast on a new design boat.
Now for the bad news. That block needs some maintenance. Either remove and finish it, stabilize it with epoxy, paint it, etc. but do something as it is starting to weather. The block takes all the compressive force of the mast and needs to be one of, if not the single greatest point of strength on the boat. every adjustment to rigging you make increases pressure on this block constantly trying to crush it (compression). So you want to be 100% confident that this is a solid block and not starting to rot or made of something soft enough to indent under load. Likely the wood type is good if the PO sailed on it but certainly a little preventative maintenance will save you a lot of headaches along the way.
Welcome to the Catalina 22 family. If you have not done so I highly recommend joining and punching the tech manual for the Catalina 22 national Sailing Assiociation. It has everything you'll need to know about the block, rigging, and mods for the boat. A resource worth its weight in gold.
Fair winds!