I think I'd get the issues with the current combo sorted out before I spent a bunch of money on parts.
My 340 with ported Edelbrocks and a hydraulic cam ran 11.60 @ 116 (1/4) on pump 93 at 3240# with 4.30 gears.
The same heads freshened with 2.05" intake valves on my 408 went 6.57 @ 104 (1/8) on pump 93 at 3260# with 4.10 gears.