[Kevin in NJ]

Yes, you can have wonderful looking paint and pure rust underneath.

I needed to practice (well still need more) painting a gas tank. So I did almost nothing to a fairly pitted messed up gas tank (it would leak as fast as you put gas in) and laid down some lacquer filling primer I had laying around and sanded smooth. Then painted. Tank looks nice even years later.

The rust under the paint is a long term issue. It all hinges on how much moisture is locked up in the layers and how much can get through the paint. Yes some (mostly older) paints are porous over a longer time frame. The rust will expand and push the paint out. The other issue is rust is not well adhered to the metal and the paint is adhered to the rust.

Ask around you may find a decent set of rims local. For evaluation I suggest you take a correct original lug nut with you. The lug nut should not be able to stick through to the back side. If the counter sinks are worn that will play some into the value of the rims and you will be ok getting the special washers to fix the problem.

I suggest that any rims you end up with that you sand the backside of the wheels where they touch the brake drum. Any paint here will wear off and cause the nuts to get loose. Any uneven application of powder coat (very likely) will warp your drum significantly.