I prefer a wire brush in a drill to clean the crud and rust out then treat them with phospheric acid and water mix (Metal Prep in the POR15 world but one HELL of a lot cheaper!) to stabilise any remaining rust then swill with water, dry and coat with oil. Same treatment to stabilise rust in the tank, two pints and swill it around over 30 minutes then drain and dry with a hot air gun. It's re-usable as well. Then use the POR15 coating which is excellent. My CD200 has been done for a good two years and it's rust-free and the coating is still in one piece. I cleaned the loose rust out with nuts and bolts, water and a good shake!What are you going to clean the bolts with James, you could try the Harpic Power Plus that I use to clean the petrol/fuel tanks out with.
This time I'm lazy with the bolts though. I've bought four new fine thread M10 bolts!