Well, it depends on if you're used to it. It's hard on tires. It not only wears the rear ones (due to the fact the inside one will always be spinning around corners) but your front ones will get pushed and scrubbed a lot. If you change your driving habits then it's not so bad. You come into the corner a little faster than an old man and set it up so you preload the front end and unload the rear.
I wouldn't do it on a K5. There's too much weight on it and it's got a short wheelbase. Not only will it handle funny (pushing around corners) but it'll be hard on that 12 bolt you've got since it's got all that weight on it. If you had a 14 bolt I'd say give it a try and worst case scenario is that you change the carrier back.
I had a longbox S10 with a 12 bolt with a spool in it. It was alright to drive since there was no weight in the back (except for a permanent tonneau cover). Then again, you powered the thing around the corner anyway. 400 horses via a sixpack and a cam that made vacuum accessories useless, 4.10 gears, a full manual turbo 400, and 265x50r15 tires made it interesting anyway. A 12 gallon tank didn't get you very far when you only got 4 mpg.
Anyway, I wouldn't run a welded rear end in the back of a K5 for street use. You might want to give it a try though. If my Gov-Loc in my 14FF doesn't work I'll be welding it--but it'll be in a longbox standard cab truck.