The motor “should” easily make in the 675-700hp range.
(MarkZ’s 505 with ootb TF270’s, gasket matched 337, similar sized cam as yours made a tad over 700/700 on the BES dyno).

Unfortunately, poorly set up street cars(especially those with a manual trans) rarely reward their owners with time slips representative of how much power the motor makes.

This is an example of(one of the many reasons) why I dyno anything I build.
If the motor had been dynoed, you’d know what it made, had it all tuned up, and have a reasonable idea of the potential performance in the car.

If the car was underperforming, you’d know it wasn’t the motor, so you wouldn’t waste time and energy trying to find the lost performance there.

At this point, the chassis dyno could be helpful.

FWIW, there is no such thing as a “good” dial back light, imo.

On the moroso chart 118@4000lbs shows 505hp.

With a reasonably well set up street/strip car, my experience has been that you should be able to run within 10% of the engine dyno numbers(provided they aren’t inflated).

If I assume the less than optimal manual trans set up costs you another 5%(15 total), and start at the low end of the predicted power output(670hp), you’re looking at running speeds that correspond with 570hp........ which would be 122.5mph.

However, without the dyno numbers....... we don’t know how much of that missing speed is lack of power, and how much of it is poor car set-up.

On a dyno jet with a manual trans....... you should be near 600rwhp, unless there are some serious fuel supply or exhaust system issues(or the motor is just down on power).

As an example of how good it can all work...... 69 A12 car in FAST......3900lbs, 600hp, 4 speed, g70-15 bias ply tires, ex manifolds...... 129mph in some killer air.