340 Intake manifold help

That carb doesn't work with that intake period unless you use an adapter. That would not be my choice combo to do. Better off with a Weiand Action Plus or a previously modded LD340. The mod you can do yourself if you wished to. A die grinder and gasket to trace is all it takes.

The stock intake and carb are capable.

What is the cam specs and gear ratio?
What is the intended target and useage of the ad?