How many years has Geets been doing this? Is it something that he has been doing only since becoming an "older" kitty?
He may be arthritic and in a bit of chronic pain, so it actually hurts him to be petted in certain areas, or for too long. Try and see if he reacts with violence when you pet over a certain area, or if it's about the same amount of time each time.
When was the last time he had a vet checkup for chronic conditions and the like?
Cats usually give off "warning signs" when the petting has gone on for too long. Flattening or rotating of the ears, squinting or widening of the eyes, tail lashing, and expansion of the pupils can all be warning signs that kitty is about to strike. You can try giving him some seriously brief attention - literally one or two seconds of petting and scritching - and stop long before you cross the mystical "too long" line. Geets probably won't be satisfied, but ignore him for a bit, and then give him a brief bit of affection again.
Or, when he scratches and bites, simply grab him, place him on the floor, and say "No" (or equivalent) firmly. He will probably jump right back up, and at that point, see what he does. Try the brief bit of affection thing at that point and see if he lashes out, or is calm.
I don't think punishing him is going to work well. He may not really comprehend why he's being punished, and he'll lash out more. I think if you ignore him outright, he may also lash out simply because you're not paying ANY attention to him.
Feliway is always something you could try - it's usually used for calming cats down, but I've been told by my vet that it also helps cats who scratch and bite.
FELIWAY - Official Site