Dawny, you never know what is going to happen - my father in law sold the house to us (we all lived together) for a low price. The lawyers were concerned that we were not doing this to dodge having to sell the house if and when he had to go into care. He was fit and well - ate healthily and exercised regularly (fell walking and cycling). Around his 80th brthday he started having hallucinations, and was eventually diagnosed with dementia (Lewy Body,not Alzheimers). It was distressing for all of us as he deteriorated, and eventually he needed 24 hour care which we could not provide, as we had young children. We were very lucky in that when he went into care we never had to pay a penny, but had he been taken ill a couple of years earlier we would have lost the house. I am not sure what the law is now, so I would advise you to consult a lawyer if you want tot go through with it. Have you also considered power of attourney if he ever becomes too ill to look after his own affairs? The law has recently changed, so again you need professional advise but it is very much worth it, if only for peace of mind.
I wish you luck, and hope your father stays in good health.