Match this 500hp/500lb-ft Combo?

The BP 408 makes 494tq/465hp with Ede Magnum heads and a 235/242-110 HR cam.

Whenever you see the hp is lower than the TQ....... fundamentally it’s an air flow deficiency in the upper rpms.
Whether that’s from the cam, manifold, heads, exhaust, or a combination of those things.

My guess is the pinch area of those heads is a restriction, and that coupled with the mild-ish cam timing isn’t letting the tq curve fall off gradually enough to allow the math to work out favorably for a bigger hp number.

Porting the heads should do two things...... boost the specific tq output, and help with flattening the upper side of the curve.
That might be enough to get it to 500hp(will be dependent on the level of porting).
If it still falls short...... add some cam duration.

Of course, starting from scratch, subbing the unported Ede magnums for TF heads might be enough of a change to push the numbers over 500/500 with no other changes.