Brake dust on my Vectors

[farmall]

I acid washed and soda blasted my used new to me A.R. Vectors almost a year ago.
There was heavy organic and metallic deposits on the inside, so after cleaning I brushed on gray Rustolium on the inside so it would be easier to keep clean. Now I have something sticking to the natural cast areas between the spokes on the outsides of the fronts.
It does not come off with a power washer.
It looks similar to the late model Vectors with a gray painted area between the spokes now.
What kind of pad is best for my situation?