Quicker off line acceleration

[Rob 71 chevy]

I was told that if I put a spacer between the carb and the intake, that my power would kick in at lower rpms. Right now, I can feel it really kick in at 3500 rpms, which is higher than I would like it to be. I don't know all of the specs. of the motor, but here is what I was told when I bought the motor from a friend. 1971 350 4-bolt, 71 vette heads, 2.02's - ported/polished, 3angle job I believe, 68 Z28 high rise intake, 670 cfm Holley street avenger, 280 comp. cam, 1.5 roller rockers, not sure about pistons, 10.25 compression or 10.5 I think. And, I only run premium. I am not a real tech. when it comes to specs.

Thanks.