Hello Robert
I was lucky when I owned Tulena, my 22, as the keel had previously been removed. Stainless steel bolts had replaced the original steel bolts.
If your original steel bolts are still in place they almost certainly will need drilling out, that I understand is quiet a job.
With the bolts out the neoprene blocks can be removed and the boat can be lifted off the keel.
I would not be too worried about the keel itself but what needs close examination is the inside of the keel box. On Tulena the edges of the neoprene blocks were cutting grooves in the fibreglass. I filled these with 'hard' filer and rounded the corners of the blocks before refitting.
I cleaned the keel with a hammer and power sander to remove the worst of the rust, Primacon in several layers was still holding most rust back several years later.
I hope this helps you in deciding what to do.
Philip Linsell ex Tulena, now rascal ss 26