Avogel, am I following you that your looking for a UB for traditional WB top colors, not HSA top colors?
If that's the case, just go with a trad WB white UB. That WB white can be a little higher in solids content but shouldn't be a full on HSA if receiving WB colors on top.
Hopefully that makes sense trad WB<=>HSA is a spectrum and there are options in the middle to some degree. The key is to decide, up front, if you are printing to bridge and form a solid film (HSA) or to wick and, essentially re-dye (traditional WB/DC). You get in trouble when you try to do both in my experience.