RE: Using a Chinese 4 wheeler for a base to make a Giant scale Car or truck.
Lots of people have done it.
Of course, if you just stick a couple of servos straight on to it, it won't be much fun.
As mentioned above the suspension won't work as it's rated to carry a person.
You'll be best off stripping all the componenets off it and building a new frame, sitting the motor lower and changing the suspension.