Correction, Holley carb is a 3310
Or should I just stay with the early 70's Z-28 intake?
My personal opinion again, I would not change the manifold unless you are planning to up your game as far as carburetor capabilities, I think you will be making a lateral step.
The Victor Jr. is a good manifold though.
edit; I think your carburetor is holding you back more than the manifold.
GT