Powder coating the tub is the way to go. However there a number of issues to deal with... a good powder coater is very important, sand blast vs. acid dip, removal of under coating, the car leaking sand for YEARS, acid bubbling etc.!
Here is a picture of my recently powdercoated RSR Clone. We had the body panels painted after powder coat. As with any type of finishing, it is only as good as the prep work. Its a labor intensive job, but IMO worth the results. Mine was primed with a powdercoat zinc rich primer, sanded then color...2 coats.
good luck!
