I am asked quite frequently if I ever use "regular" acrylic miniatures paint over figures that I began with oils. The answer is yes... all the time!
Once the oil paints dry (which can be a matter of hours if you use the Mig Ammo Oilbrushers and thin your other oil paints), you can seal them with any sort of Dullcoate, and paint right over them with no troubles at all.
I thought I would film a quick video last week as I did this very process. Originally these figures were part of a massive batch of stuff that I was painting, which is the primary advantage of oil paints. You can work on a vast amount of figures all at once quite easily.
I sealed these with Testors Dullcoate, and they were ready for working in acrylics. The original layers of oil paints would be used essentially as an underpainting.
I also made a few other changes... especially going from Non Metallic metals to metallics by using the Vallejo Metal Medium.
Here's a link to the tutorial video: https://www.youtube.com/watch?v=b6991iucjt0