AWS FMC-93 lists Astrolite Alloys, Champion International, SA de CV, Robinson Technical Products Corporation, Thyssen Specialty Steels, Inc, Washington Alloy Company and Weldwell (NZ), Ltd. An internet search will find the addresses and contact information.
I'm wondering where you got the 25% elongation for the 6020 rod. AWS A5.1 has elongation minimums of 22% for E6010, E6011, E6019, E6020, E6027, E7015, E7016, E7018, E7027, E7028, and E7048. E7018M has a minimum of 24%, but none higher than that. I also looked at some E7018-1 certs with actual tests and elongation varied between 27-35% in the as-welded contdition. That should be plenty ductile, plus E7018-1 has a high toughness too. For cyclic loading, fatigue strength and toughness (resistance to crack propogations) are usually the most desirable properties. I don't know what kind of toughness E6020 normally has but there is no minimum specified in A5.1. For ductility and toughness, either E7018M or E7018-1 should fit the bill just tine and are more readily available not to mention thier are all position operability.