My vote goes 100 percent to finding a semi float 14 bolt. The first Chevy I drove was a suburban with 8 lug version- it was driven hard for years. They are out there in 6 lug. I put one under the back of my blazer years ago, and have been more than satisfied. I paid 500 bucks to have it delivered, which I thought was a bit high, I did have to weld new spring perches on (cheap- just need grinder and welding capability) and even the factory gov-bomb has never given me or my friends probs in this axle. Mine came out of mid 1990s z71 pick up- it is just slightly wider than the origional 10 bolt. Its almost exactly the same track width as the front- I like the way it looks and zero complaints about turning radius and handling. I did not need a conversion driveshaft, or u joint, or new flange- the stock driveshaft bolted right to it. My 6 lug wheels slapped right on- needed metric lug nuts though. It had about 70 thousand miles on it it when I got it- I popped the cover- everything was there on the inside and looked alright- cover back on and started installing.
60 thousand hard miles and 7-8 years later zero problems. (I changed the oil once or twice I think). If you aren't rebuilding the entire truck, I think the semi float 14 is almost perfect choice to end the 10 bolt rear end probs. I would over pay for one again in a heart beat. I would grind of old perches and pay someone to weld the new ones on if I had to.
