It's great to hear that others are building off this platform. They aren't as super comfy as some other options that's fit sure. The rear height is a bit tough for taller folks. I'm working in Bristol bay again this summer and happen to be in a village where several of the set net fisherman/women use 1980's gmc/Chevy s on the beach exclusively. This is probably one of the toughest environments with the salt water and sand. There are at least 8 cucv military trucks and a dozen more civvy versions. It makes me feel reassured that the old Chevy platform is bulletproof.
As far as doing a build on a budget I'm pretty convinced that it is possible. Huge tires and lifts drain pockets quick. It's free to cut fender wells and medium tires aren't too expensive. There are some costs that are unavoidable but can be mitigated with creativity.
Once I became happy at driving 55-65 mph on highways, I have pretty much just enjoyed the truck for what it is. A slower, reliable, go nearly anywhere rig. That gets decent fuel economy. If you have to be worried about driving more than 55-60 in my opinion your doing it wrong. The only other owertrain change in making is the turbo banks kit. After putting a decent amount of miles the only thing it needs is to breath a little better at altitude.