I'd just smooth the trouble areas and project again. If the lowpoly doesn't match the highpoly, you'll get those results in the first image. You might also want to Geometry > Freeze SubDivisionLevels > select the Zmodeler brush, and alter the lowest subdiv so that you get better projection results
You may need to fiddle around with the projection settings a bit (try the distance slider first, and if that doesn't help you can try messing around with the projection shell) to get a proper result.It doesn't look like there are too many closely overhanging parts on the sculpt, so that should be enough. Another more…