Yikes! That engine's potential is definitely higher than 560hp. I would presume a carb spacer, and intake porting/swaping is in your future.
I know it is never a good idea to race dyno sheets, however...compare the data.
Here is a very good engine to look at. (Not my engine, built by Straitline, Owned by Caper here on moparts)
Straightline 496 info Simple, very stout, reasonable inexpensive 496" - similar to your combo.
It is in Caper's 3700lb 69 dart, currently running 10.40's
496 CID Wedge - pump gas street engine (10.7 to 1) Built by Scott Brown at Straightline Performance.
* 654 HP- 5600 -RPM
------------ - Hand Ported Edelbrock RPM heads (300 CFM) - Ported Victor Single Plane
* 653 TQ- 4400 -RPM
------------ - Flat tappet, 263/273 @ .050 112LSA - 4150 Carb ( Quick Fuel 1050-AN) - 1" tapered spacer
Somewhat lesser flowing heads, but definitely a better breathing intake setup.
