I just used some eastwood encap. works nicely and is u.v. stabile without topcoat. If you're even thinking about spraying the encapsulator is my choice.
Everyone has there own opinion on this. I used POR-15 and really like it. If you go with POR-15, just make sure you treat the metal the way they tell you. if you leave the metal prep on to long, it will leave a white haze, and if you paint over this the paint will not stick very good. Just my 2 cents on this product.
i have used the eastwood stuff on a daily driver before and a couple years later it was all rusted out again. all this stuff does is slow down the rust.