The only lowering on the rear was to relocate the rear mount for the lower control arm. The fronts are coil-overs, so yes, just adjust to suit. Both these suspension heights were set from my previous wheel and tire setup ...
These are 245/50/16 (25.8" tall) front and 255/50/16 (26.2" tall) rear. The tire diameter makes a difference in how it looks in the wheel well. The current setup is 255/35/18 (25.1" tall) front and 275/35/18 (25.7" tall) rear.
Sorry for such a long wait for a reply....had some issues here. There are quite a few companies making coil-overs for the Foxbody, but my customer decided to go with a lower priced kit (about $1000), and he is very happy with it. This car is also a 306 with a Vortech and a T-56, and that has not seemed to be a problem.