Custom ground camshaft, low power

Forget the chassis dyno numbers. The numbers will vary a lot from dyno to dyno. Even how tightly the car is cinched down will have an effect. The dyno is for tuning and testing parts, not for telling you exactly how fast your car will be. Take the car to the track and see how it runs. There is more than one 11 second car out there that makes "only 310 hp" at the rear wheels. I would say your biggest component issue is those damned puny headers, not the cam.