make a 4x4...
bunch of work... but...
the ford f450 and f550 were used for shuttle buses, ambulances, and rvs.
I would think if you got a chassis based on the ford you could add, trans modifications, transfer case, front axle assembly from 4wd. a bunch of work. I would start with a donor truck that had the same engine and work from there.
I have seen a book mobile bus that was front wheel drive, they started with a 4wd and deleted the rear drive shaft. I thought the transfer case would be fragile.
I dont know about chevrolet based chassis.