The head porting likely added around 60cfm...... With a radius plate on the port opening.
The RPM is a bit of a flow restriction, so with that in place...... And depending on which manifold runner you're testing....... The gain would be more like 30-40cfm.

Usually it comes down to this......... If the flow of the heads/intake manifold were the major restrictions to the performance of the car, then improving them will yield big gains.
If you dont see the kind of pick up you're expecting....... Then they weren't holding you back as much as you thought.

With the RPM intake, on that combo........ I'm going to say a 40-50-ish hp improvement.
So, if you get that much improvement in power, and make the best use of it, at the current performance level of your car........ 4mph and .4 ET.

My gut feeling is more like 2.5-3 for both ET and speed.
Maybe more with some tweaking.