X2. Chassis paint is made more for the grime and crap you encounter on the road. It protects the metal and prevents future rust better then anything else you will find just because that is what it was designed to do from the start. It will also stay cleaner and hold less dirt since chassis paint is smooth. Bedliner is great, but it holds the dirt in the texture quite a bit more.
Complete rebuild axle/engine/everything swap in progress:
Parts already gathered for assembly: 2001 Ford 302, 1990 Mustang GT 5.0 ECU and wiring, NP435, NP205, Pair of axles from 04' F350 SuperDuty (Sterling 10.5 Posi rear, Dana 60HP Front-Both Disk Brakes 3.73 Gears), 37" H1 Tires, 9" lift TJ Coils for 2 link conversion in front, Stage 2 Clutch Kit, 3 Row Aluminum Radiator, Chevy Astro Steering box (4" front Stretch), XJ Rear Leaf Springs (6" Rear Stretch), and lots more.