Well then you need to look at the contract documents and find out if there's any preference included or notes from the EOR (Engineer Of Record) and if none are listed, then the next step would be to make an RFI (Request For Information) to the EOR for clarification as to which filler metal to use...
Btw, What is the welding code or standard these qualification tests being set up to??? Is it AWS D1.?, ASME Section IX, NAVSEA/NAVSHIPS, NASA, etc.???
In other words, what I'm getting at is that you as the welder should not be left to making the decision alone in choosing which specific filler metal should be used for a qualification test if there are certain individuals up from you in the chain of command who is indeed responsible to make those decisions... So if I were you, I would follow the chain of command up to the EOR if necessary for a clarification via an RFI so that everyone is on the same page, and later on no one comes back to you and says: "You did not have the authority to decide which filler metal would be used for those qualification tests!!! You're just a welder here for cryin out loud!!!" So please take this as a piece of advice... Let the folks with the fancy titles make those types of decisions unless that is - you're one of those folks with a 'fancy-schmancy' title as well! :) :) :)
Respectfully,
Henry