I think I would hold off on the headliner. If you still have paint work to do your going to have overspray and all of this will need to be tapped off. If you have the interior of the cab already painted the gauges and such shpould be fine but any carpet seat material and cardboard panels will all need to be masked and sealed up tight. I think I would hold off until all paint work is done before I do any interior panels. This would be my concerns.