We painted the inside first. Started by painting the back side of the dash and underside of the cowl with white paint - just brushed it on. Painting it white helped when installing gauges, wiring fuse panel etc. as the white paint makes it easier to see while you are on your back with a trouble light. While the cab was on the firewall, we painted the inside (epoxy primer and colour coat) and the underside (epoxy primer, endura and undercoat).
