Staying with 6 lugs is going to limit your option alot. The only ones I know of are:
1. Get a new set of 3:36 gears for the rearend you allready have. 3:36 without overdrive is still fast enough to get speeding tickets.
2. I have heard of guys using a rearend from a 70's fullsize Blazer 4X4, but I think it's a bit wider, so you may need to get rims with a different offset.
3. I have heard of guys using a rearend from an import pickup, Toyota I think. 6 lugs is 6 lugs, the pattern is the same from everybody.
Driveshafts, emergency brake cables, spring perches, shocks, brakelines will all need to be addressed when making this kind of change. If you take a closer look, you will notice the centerline of the axle is not centered over the spring center bolt either. So don't forget to drill a hole in the perches accordingly.
