A rearend swap is what you'll have to do. You could try an S-10 rearend. It's perfectly o.k. for the 6 cylinder, but if you plan on a nasty V-8 I would look for something a littlle beefier. A rear of an 80's era 1/2 ton or van should more that suffice. For the front, that's another issue. There's no brake upgrades available for the 3/4 ton. You could do a whole IFS swap or have some bushings installed into your axle and swap your spindles for some 1/2 tons.
