Those are two different products. M205 is a finishing polish and PoliSeal is a sealant as far as I know and won't offer any correction.
If it is oxidized I would go opt for the M205 followed by the PoliSeal. Claying first might help also.
Make sure after you've sealed and when you're ready to put on the decals that you go over that area with some alcohol or something that will strip your LSP. You don't want to put decals on over something that has sealant or wax as it won't stick very well or very long.