Q: And what sort of an honest man are you?
A: I'm a sort-of honest man.

This is indeed a good candidate for Guttman Rosler. But note carefully. He wants to sort some keys ascending, others descending. In addition to the pack, he'll need a transform which will turn descending keys into ascending ones (or vice versa.) E.g. subtract each descending key from 1000. That will only add trivially to the computation time. But it will add another layer of difficulty for the maintainer's comprehension.

throop

But many that are first shall be last; and the last shall be first. — Matt 19:30