Overpainting eco-solvent inks

My first thought is, are you sure that the colors on the eco print are lightfast enough to be used for fine art? I have not tried this so what I write must be tentative. Have you tested the ink for solubility in oils or any organic solvents that you intend to use? This could be done on a disposable print. This would be a good place to start. However, if the print is at all absorbent, the application of oils will likely saturate the print changing it in ways that may not be pleasing (think of grease on a sheet of paper).
You could also cover the print with a very thin layer of an isolating material. If you check and the print can withstand water, I would suggest an acrylic dispersion medium. This would create a more acceptable surface.
Finally, I have not tried this and you should really make a mock-up and test the procedure before attempting it on your artwork. Hopefully, others hare are more knowledgeable about this material and can comment with more authority.  

Since this ink is solvent based and not water based (which means it would have surfactants to worry about) it is likely that the oil should bond well to it. Testing is absolutely necessary and it should be done in real scale and allowed to age naturally.
Hugh Phibbs

Any profession brand of acrylics (not student or beginner grade) should offer a suitable medium. MITRA does not endorse specific brands of similar products over another. I looked at a NZ art materials supplier and saw a few profession brands of acrylic dispersion paints.