Dropships, even loaded with weapons aren't the greatest for air to ground work. They are expensive to start. In C-bills, BV, etc. For strafing attacks I find ASF with high speed and a large number of weapons such as the Samurai works well. Your tohit for strafing automatically adds +4, so having a good gunnery skill helps A LOT and so does having a lot of weapons to choose from. For ASF and Small Craft the lighter weapons are usually better as it means more chances to hit. Strafing is already hard enough with a regular pilot. The more energy weapons you have to point at the ground the better. Luckily the heat is only tracked at the first shot.
As expensive as dropships are it is not something that one would want to use for ground attacks. It is possible, but the cost is better spent on small craft or medium/heavy ASF with LOTS of energy weapons.