Valve spring options

I have a Lunati 513 533 lift. 234 242 duration vodoo cam in my 71 340. The double springs that came in the kit are too much for the lifters. Did the break in with the singles and all quiet. Put the doubles in and once the motor heats up they get noisey. I do not race this car. I street drive cruise. Never gonna go over 6500rpm. Doubt it ever sees 6000. What would be the best single spring to get the job done? The Lunati springs dont have a damper so I dont want to just use those with the centers out. Thanks