Will a 79' 12 bolt work in a 4th gen?
You'll have to cut off the leaf spring mounts and weld on your own LCA and shock mounts. For the torque arm, you're on your own. If you look at the Ford 8.8 information in the rear axle section here, you'll see how some people have grafted torque arm mounts to non-torque-arm rear ends, but half the time they ended up breaking off. Welding to a cast pumpkin can be tricky.
Not sure if your brakes will bolt up either. I know 94 LT1 rear brakes (with mounting plate) bolted up to my 79 Z28 rear end (pulled the drum stuff off), but one side didn't clear the shock mount on the 79 rear.





