I can't answer that, the question begs the question; what do you consider "truly high floating"? Also, are you asking about the hard plastic (Alumilite) or the soft plastic (alumisol)?
Regarding the hard plastic, check out the lure photos section to see a graph I did on microballons in Alumilite White.
http://www.makelure.com/Lures.cfmI have not done a density curve with Alumisol. When adding Microballons to Alumisol, it hardens the plastic, and clouds the plastic, so you have other issues to deal with as well. I usually expect the clouding of the plastic, and I add some softener if needed to reduce stiffness.
I guess that the answser is that this time you will just need to experiment. Perhaps in the future I will have the money to buy some Alumisol to experiment with a density curve.