Which Vacuum secondary spring are you running on 4053-DZ 780

[WaltZ]

Which Holley Vacuum secondary spring are you running for the 1969 z28 Holley 780 4053 with the standard duntov speced cam.
Looking to have the secondaries fully opened sooner than 5600 rpms under load
thanks in advance
W

[cook_dw]

What color spring are you running currently?

This is the basic secondary spring chart from Holley.  I'd suggest getting a spring kit and a quick change cover to dial it in and then swap back to original top if you truly wanna tune the carb.  If those aren't satisfactory then go to a mechanical secondary carb.