Engine air filter is a must. Cabin air filters are suggested.
While you have the belt off, look at the water pump and check the pulleys. If you are already in there, it wouldn't hurt to replace the thermostat.
If you still have the OEM brakes....... I would change the pads, resurface the rotors, and bleed the lines. It would also be a good time to refresh the suspension components. The front should be okay. Although you never know. You could find a leak or something. If the van was used for cargo, maybe rear shocks. I doubt if you will need new coil springs. And with that many years & miles...... new tires.
Maybe buy a new battery. It could very well be the OEM battery. Add some new wiper blades before winter.