1. Wow
2. Nothing wrong with a pavement pounder. Not everyone is interested in 4xwheeling, and there is nothing wrong with that.
3. I believe there are a LOT of simularities between your truck and late model K5's. 10B rear, 208 or 241 case, and a 700/L60E trans.
I have a 6" lift and ran with the stock driveshaft for quite some time. The slip yoke was pulled out fairly far, but I managed to never have a pogo stick incident. If you are just cruising on roads and you have no vibration, than the stock shaft is probably fine.
BTW, I ran a 9" lift and aggressive 35's for a LONG time and loved the look of it. I now have 36's, but plan to actually go back down to a wide 33" and somewhere around 6-7" of lift.