I was trying to do so in the past, but could not figure out the appropriate solution.
Looking at an older post about it: Density to Mass Conversion (Modal Analysis) - #2 by FEAnalyst and looking at the discussion above, the following should be changed:
mass: lbf·s²/in = blob
density: lbf·s²/in⁴ = blob/in³
All other units can remain as they are and will finally represent a consistent unit system?