To upgrade intake manifold on not?

I had same 340/X/284-484/3.91 rear in my 65 and I went with a Holley Strip Dominator. Hauled *** with a 650 Demon and before that a 750 spreadbore holley DP:ugly carb but ran great! . 3.91 really makes the car feel light and the motor/cam/2800 convertor responded to the higher RPMs nicely.