That spec sounds exactly like what I used on mine, zinc Phosphate first, black second. Ask Sherwin-Williams but it would seem to me to be the same stuff. They will sell you the paint, you will only need the black not the zinc primer, and tell you when it is made. You can then collect from works in Bolton, or Decorators Supply co will order but its much dearer and plus delivery charges. The black comes in 4 ltr (3+1 hardner) cans, you will need 2. Last I bought was around £10 a ltr.