Search this forum for "keel dimensions" or "keel drawing." I know that someone has posted a Macgregor drawing for the original build of the V222 keel, measurements and all.
There shouldn't be too much clearance. My V222's keel, before it began delaminating, had a close fit. I never heard it knock around against the trunk. Every boat is different, though. My M25 keel is cast iron, with a good pivot hole, and it clunks while under way unless I lock it down. MacGregor did build some looseness into the design, but I think some individual boats are worse than others.