Trade-off?

I have owned my 40 year-old Dockrell 22 for 2 years and she sits on the mud for most of the time, above neap tide. I have just finished removing the remains of the epoxy layer that once covered her swing keel casing. This casing is about three inches thick each side of the slot and is rusted on the outside vertical face but not to any great degree. The turn of the keel is heavily pitted like a lunar lanscape, now that I have applied grinding materials. I suppose the slot will be the same as the outside vertical face and as I only paid £1500 for her and am cheap and lazy, could I get away with laminating the visible and letting the slot do its worst? How many years might I keep sailing before the boat floats with a list due to lack of ballast?

 

I don't understand the last part. Can you post some photographs?