You should DEFINITELY degree the cams in. And to do that, you need adjustable gears. However, don't get the adjustable cam gears (like Comp sells); get the TFS adjustable crank gears. There's no 'adjustment', so to speak, that can somehow get unaligned. And they're cheap. And about degreeing the cams, my cams were SIX DEGREES from what they were speced at. Install a cam that's 6 degrees advanced....and bye-bye intake valves.
I've seen stock head, stock intake, cam-only 4.6s make 295-300 rwhp with pretty much every bolt on in the book. So I'd think you'd knock down 310-320 pretty easily. The only thing I see going against you is that you don't have long tubes.
I know a guy with a full bolt-on, Trickflow HCI 4.6. I think it only made like 320 rwhp, but runs 12.0s @ 113-114 mph on a full weight convertible. I'd say that's pretty strong, and I'd think you'd be close to that.