Fred I used paintable sika flex sealer 742 I think tough as nails not finished with it yet more to do once the other mini tub gets welded in ground and shaped.Its polyurethane.
Most sealers are good on bare metal Biff and not sure what you have but sounds good. I just choose to put sealer on just before painting.
Same here on the budget lots of money to paint a car and time. Like I told Jeff when you are ready to spray your car Biff I have extra spray guns I can send you one if you need it. Save your money.