Had my stock box rebuilt by PSC and it seems to work fine! My only complaint is that there looks to be a small amount of play where the pitman arm is attached. I don't know if that is common but overall satisfied I guess.
In terms of the quicker ratio of 3.5 to 1 or 4 to 1 vs 6 to 1 I think that it all depends on the trucks intended use. If you are gonna be primarily in the rocks then the quicker ratio is probably the better way to go but if you are on the pavement more then I would stick to 4 to 1 or even a tad slower ratio. Will make driving the truck more predictable IMHO.
My current box is around 4 to 1 or even maybe 3.8 to 1 I think and it can sometimes be a little bit twitchy depending on the road. Eventually I would like to make is a little bit slower ratio to improve the road manners.
Also, I don't know if this is thought about too often but the smaller steering wheels that we put on to replace the ugly old worn out stockers don't help things either. The larger wheels again IMHO will make the steering more predictable and help with the over corrections that sometimes occur as a result of the smaller steering wheels we are using these days! My .02!
Also, James Duff has a really nice setup that utilizes a new PS box that will bolt into the factory holes that is a stronger box as well. May want to check them out! Good Luck! ;D