Too much. Just get some 4.10s, a tranny cooler, PI Stallion torque converter and the Jerry Mod and u will kick the shiit outta a 5-speed any day. Plus it will be more consistant and u wont have to worry about missing a gear.
I agree that is highly labour intensive. I would only do that if I could do it all myself and had the parts for it for free. So basically never. I woud bet several grand with time&materials. That you are basically pissing away. Not that stick is bad, just a big deal.