Hi. You might get too much color and roasty flavor from the stout transferred to your IPA, unless you wash your yeast. Washing yeast is easy as long as you pay careful attention to sanitation. Search for yeast washing tutorial threads.
Random Fact: Human Immunodeficiency Virus particles have approximately the same density of 1.170 wort. I know because I float them on a sucrose gradient in the lab to purify them for research.
Drinking: Belgian strong golden, Northern Brown, Porter