3" travel sounds slightly excessive Gary,I assume the brakes are full bled of air?
Also bear in mind the front pads will have to work harden, new pads can sometimes feel a bit spongy but the pedal still shouldn't bottom out..
I would try adjusting the pushrod as you've suggested.
Just make sure to pay attention to the free-play and you do not retain pressure after the pedal's released.

1950 Chevy Advance Design 3100 in Scotland
In the Stovebolt Gallery
More pix on Flickr.
I've definately got this truck thing in my blood ... my DNA sequence has torque settings
"Of all the small nations of this earth,perhaps only the ancient Greeks surpass the Scots in their contribution to mankind" Winston Churchill.