If the valves are bent I would probably rebuilt the whole thing as for the tool you need you can rent it at autozone. I think its called the valve spring compressor tool magigge , you will also need a magnet thingy to get the keepers out when you press down on the valve spring compresser thingy, that releases pressure on the spring then use the magnet to fish out the keepers while still pressing on the valve spring compressor thingy. When the keepers are removed pull out the springs and retainers then pop out the valves. And its off to the machine shop. Just pray the head isnt warped or damaged.Good luck, sorry I couldnt be more helpful with technical terminology.