I ran a similar combination. Stock stroke 360, ported j heads, 590 cam, victor manifold. 904, 4.88 gear, 65 valiant. Ran 10.20's @ 130... i think you have too much gear like others have said.
That's a good running combo. When I ran the 557 purpleshaft in my 340 years ago I was running 11.70's and there was a guy with a 340 Dart there that was running a very similar combo but he was running the 590 cam and was going 11.20's. That's kinda what made me want to try the 590 in my big block car and it ran extremely well.
It's hard to go wrong with a cam and lifter kit for around $170!
Fast68Plymouth recommended a couple Comp cams so I would definitely look into those.
