In most fighters your main problem in the divebombing run is not overspeeding and augering.. Get over the target at about 10K, chop throttle, point the nose at the target. In a P-47 or P-51, you can use one or two notches of flaps to help keep you slow. In P-47D-40 and P-38L, you have dive-brakes, which is ideal. In the Corsair series, you can drop the gear at high speed as a dive brake.
Basically, I get in a nearly vertical dive, I generally put the target somewhere between the bottom of my gun-sight and the nose of the aircraft, and I drop the bomb as soon as I have a stable solution. Like the other guys said, don't screw up and wait too long to drop, or the bomb won't arm.
BTW, you can turn on a computing sight for dive-bombing in offline and TA.