Maintain it like you would your car. However, get in the habit of pre-tripping it before every outing. Also, get a feel for the condition of your oil. Oil analysis services are relatively cheap. Your higher revving small block is going to be working harder than a diesel and may be harder on oil than even in your normal car. On the other hand, your oil pan is going to have a much higher capacity. Either way I think you're going to want to change it based on the amount of time it's been in there rather than mileage. Condensation and other gunk is a killer, especially when it is sitting. Changing the oil once per year will probably be sufficient.
As far as tune up ignition it really doesn't get any easier or any cheaper. It's just small block Chevy stuff.
Chassis maintenance is pretty easy. Keep it well lubed and do an occasional inspection of everything. Fix stuff when you first see signs of deterioration rather than after it actually fails and I think you will find it to be pretty cheap and easy to keep things in working order.
The biggest thing is to just get in the habit of pre-tripping. I like to run my bus for a while before an outing, say 30 minutes. I visually inspect for leaks or signs of wear. All the easy fluids are checked before every trip, even short ones (oil, coolant, power steering fluid, etc). With air brakes it is important to check your slack adjusters for misadjustment or broken parts. Check the system performance and make sure it's working. Check all the lights on the bus. It really only takes a few minutes and will prevent headaches in the future.
